Welcome to Android. First of all, after you enter your Google email, gmail, you go to Google Play Store, check for the icon in the apps drawer. In the search bar you're going to ask for clocks, icons, etc. There are apps for rooted phones that can't work on stock phone. So for now just download stock. My LG G2 runs on stock AT&T, I don't know much of rooted phones. The better way to learn about apps is reading the apps definition or explanation before you download. Some apps are free and have prime or pro versions that you must paid for. For now let's talk about launchers, Nova launcher is the most used one by the majority of android phones owners. There are many launchers there at Google Play Store; Apex, ADW, GO. Just ask in the search bar for launchers and you will see. Try them all in the free versions and them if you really like one in particular go for the prime or paid version. You have a long homework to do in Android, take it easy everybody here start from ground 0. Enjoy your LG G2 and visit the forums; Android Central, Android Forum, XDA Developers. You want to learn, you need to read. Good luck, by the way I got lots of paid launchers but my favorite one is free, Holo Launcher HD

 

Generic Jelly bean manual here
Android 4.1 Jelly Bean User Manual Guide | PDF User manual Download

Google LG G2 manual and you can download a manual specific to your carrier.

Launchers are the primary User interface management programs that handles your home screens and the icons you place on them. There are many that can be installed and will replace the default one.

My strong recommendation.... stay with the stock or default launcher LG has provided. It's very feature rich and customizable. When you become more familiar with Android, then I might recommend a replacement. Until then, you'll have plenty to tweak and thus call the phone your own.

 

First off...... Welcome to Android Forums......... and welcome to Android.... youll never look back

lets start in the middle of your questions.....

whats a launcher...... a launcher (in simple terms) is what controls the operations........ most importanly your home screen/s, application drawer, etc......

on this phone it seems a good split about half love the stock LG launcher (which is what you have and are looking at right now).... and about half (those who are used to subpar launchers on previous phones) want a 3rd party launcher.......

there are many launchers available in the Google Play store....... Nova is the one that I prefer because it seems to sit right in and compliment the stock features of this phone...

WHY? would you want a 3rd party launcher...... because it adds more customization features....... you can do things with 3rd party launcher that you cant with the stock....... bare in mind all of these things are asthetics (what you see)..........for instance..... with Nova one of the main reasons to switch is the ability to make the Notification/Status bar at the top of the screen invisible..... you make a drag down gesture on the screen to make it appear....... this frees up viewing space on the screen.......

of course as I said each launcher has its own special tricks and tools... I cant tell you what you may like...... so each to their own....... like said.... about half prefer just using stock...... which on this phone is bountiful and brilliant

now on to the rest....

wallpaper: any launcher (including the stock launcher you already have) on android provides the ability to change the wallpaper...... something you may not be familiar with coming from iPhone is the ability to use LWP (Live WallPaper) these are animated wallpapers (a popular one is the lifelike aquarium)...... its simply a matter of downloading a wallpaper (and installing in the case of LWP) thats designed to fit this screeen size (1920x1280) (LWP fit all screens).... then clicking on the settings button (if memory serves me its 3 lines on stock) on the navigation bar at the bottom and selecting wallpaper...... then scrolling to the wallpaper you want and selecting it

icons: youll have to forgive me for a moment because I dont use stock launcher.... but if memory serves me I believe youll need a 3rd party launcher for most icon packs... with a different launcher its simply a matter of downloading/installing an icon or theme pack .... again goto the settings button on the navigation bar... select settings (heres where different launchers may vary)... on Nova you would select Look and Feel... Icon Theme........ but regardless of the launcher (perhaps even stock) its very simple to change........ and there are uncountable sets available in the Google Play store

clock, weather, news: this is where it gets even more difficult to offer advice.... Ive never used anything but 3rd party applications for any of these.... and I dont know many people (Im sure theres some but I would guess a strong minority) who do....... there are literaly thousands of apps for each of these items.......and most will find one that suits their individual needs and taste

I apologize for being very long winded...... but again I welcome you to the Android Forums....... hopefully you will find all the help and fellowship this site provides to many users

PS: since youre new to Android I will tell you what "root" is..... its a term you will hear quite a bit....... its somewhat the equivalent of "jailbreak" on an iPhone........ it gives administrative privs (complete control) over your phone...... which means you can change a lot of system settings and software that you cannot do with stock software

 

Copestag's point:

on this phone it seems a good split about half love the stock LG launcher (which is what you have and are looking at right now).... and about half (those who are used to subpar launchers on previous phones) want a 3rd party launcher.......
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is a very good one. One way to see better UI responsiveness on a phone was to replace the stock subpar user interface / launcher. I think it fair to state the launcher wasn't the complete UI, but the primary program that you'd be interacting with your device on a regular basis.

Some people also resorted to more involved customization: rooting their devices (in the Linux world on which Android is based essentially giving themselves "root" or super user privileges) and replacing the phone's operating system so that they could move away from the customizations the carrier and phone manufacturers made to the Android code base. They also found on devices with specs, generally far lower than the LG G2, the overall usability of the entire device was better, because those replacement ROMs were optimized for speed and to use a smaller amount of the phone's limited resources: CPU and memory. Some people also wanted to run more updated versions of the operating system. In the Android world, not all phones get the latest and greatest version of the OS, like they would with iOS. Or they simply could not look past glaring bugs that handicapped important aspects of their devices... while waiting for updates to be made available.

You can't really do any damage by installing a 3rd party launcher. You can always revert back to the stock experience by uninstalling it.

My recommendation that you stick with the stock launcher was based merely on the fact that it is highly customizable and responsive already, and since you are new to Android, your experiment opportunities are already wide and deep.

One way to become more competent in configuring a device running the Android OS is to experiment. And, my intent was definitely not to dissuade you from doing that!

Have fun!