1. Yes you're phone will be fully operational after flashing
2. Best rom kinda depends on your preference of what you want, head over to all things root guide in the all thing root forum to see rom list. though Monster 5.3 and OA are still the best at the moment.
3. Most roms are debloated but you have to remember what you consider bloat may not be what the maker of the rom considers bloat. for the most part yes roms are usually fully debloated.

4. you really shouldnt be worried about bricking your phone, if you take the proper steps to prevent the worst case scenario(which is the phone stuck in a bootloop) then you will be fine. the proper steps are making a backup after installing CWM by reading the thread in the all things root forum. and just make sure you read the flashing instructions. i feel like if someone fully bricks our phones beyond repair at this point in time you kinda deserve it for not taking the proper steps

 

so should i install a new rom on stock 2.3.4 is it possible? and will work faster with more memory?

 

Most roms are for 2.3.4. Most have speed tweeks and some memory improvements .
Theres alot of em. So read,search, read,make backups,and flash em all till you find one you like.

 

ya i have been doin some research, i havent heard if your able to without rooting my phone? ive been makin sure i read up backing up my phone to nandroid or even using cwm. i understand thats where people usually mess up or brick thier phones! Can i do it? lol i know it probaby gets repetetive but thank you!!!! ive been thinking Mystery Emotions rom admiral beast though

 

As far as i know you must be rooted. Admiral beast was the 1st rom i flashed on my phone. Its a good one. As for bicking the phone, follow instructions to the t and it wont happen.

 

No you don't have to be rooted to flash roms with THIS phone. As long as you have CWM you can flash, backup, and restore. Which is recommended you install first and then create a backup so you can restore to stock. Flashing a rom will however root you seeing how roms are all given superuser permissions. And people don't really truly 100% brick their phones while flashing roms seeing how it can easily be restored. SO AGAIN AND I SAY THIS IN CAP TO FURTHER STRESS MY.ALREADY MADE POINT. MAKE A MAKEUP, THIS IS THE FIRST THING YOU.SHOULD DO!!!

 

FYI -To the root side