i9001 problem

[lexz]

Hello. Yesterday I decided to upgrade my i9001 to 2.3.6, from my carrier it came with 2.3.3 ... and the battery ... damn, the battery would let me play a few hours/day (let's say 1-2 / depends what game, Six Guns 30-1h then battery is empty) and 2 hours of music which is really dissapointing compared to my old Galaxy Mini ...

So ... what went wrong ? Well, not much, I've got some "ROMs" from XDA but, but ... they're modified ... they are not clean, they have aditional programs and such things which I don't really want. I've searched for a clean ICS but ... nothing.

So, what I need right now:
- What is a "ROM" ?
- Can I find a clean version (to install on my phone) of 2.3.5 / 2.3.6 ?
- Can I find a clean version of ICS for my phone ?

And also, I've got a file "I9001XXKPU_I9001XXKPH_I9001DBTKP1_HOME.tar.md 5", this is for Odin ?

I hope I've posted in the right category. Please excuse my bad english.