They run on start up so you can quickly select whatever you're using the phone for inititially. So say you turned your phone on for directions. com.google.android.apps.maps is already running so you can do that quickly.

They're all taking up memory, but you shouldn't really notice any lag unless you start loading up lots of 3rd party programs.

Eventually anything you're not using (setting calendar, mail etc...) will be auto killed by the OS.

If it really bothers install TasKiller from the market.
All you have to do is touch the process and they end.

But obviously don't go ending Scense or Android system

 

Hmm, that seems odd.

Low battery life is no secret.
But mine chargers quite quickly (fully charged from 15% 3 hours?)

Try letting the battery completely diminish until the phones LED's don't even flash to say low battery. The charge up FULLY.

If you can't be bother with that, use taskiller.
It should help a little.
Although it's rumoured to only help short term.
Long term it's best to let the phone auto kill things.

 

If you have any widgets they run when you access the home screen it is on. As far as some of the programs on your phone. Battery Widget may be causing battery overload because it always has to access the the battery information causing more drain. Meebo IM has always gave me problems and thats why I use E-Buddy (it also offers more features). I'm not sure why you have an application for mounting USB because the Android Operating System has that built in your notifications when you connect it to the PC via USB...

Just some thoughts... You may also want to try ATK(Advanced Task Killer)

 

I've read in other threads that people that don't use task killers are experiencing good battery life, well good for the Eris I guess. What if I open up Google Maps? I can't close that down without a task killer right? Won't it keep trying to triangulate me using the cell towers and eating up my battery? I'm just wondering.

 

I've seen lots of posts about why task killers shouldn't be used but without using one my phone has to be near a charger by about 12 o'clock. Using one gets me right through to the end of the day. As a general rule most apps go on the ignore list, leaving only 3rd party apps/games and some of the less necessary core apps like maps, stocks, footprints, etc... When the phone starts to lag it gets a reboot.

 

Apps that use notifications are the most battery consuming in my experience. Craigslist, two email programs, weather - they all use more power when their updated frequencies are high.

You might want to look into rooting your phone. You can underclock it while not in use to save battery life, and get rid of a lot of the stock apps like AmazonMP3. I have been getting better battery life since doing it.