Hi,
This is a two part question 
i'll try to make it as clear as i can.
First I'm interested in update the arduino bootloader (for my MEGA2560 R2 board, and i'm using IDE v1.0.4) i bought the board some time ago, so i guess the botloader will be much newer now than the one preloaded.
so... Where is the right bootloader to burn on my board?
I have been looking for information around but i ended up a bit overwhelmed because there are a lot of information but none of it make it completely clear for me and i don't want to break my board 
I have an AVRISP V2 programer that i guess is the right tool for bootloader burning, isn't it?
My second question (about bootloader aswell) is:
How can i edit the bootloader to be able to identify on my sketch the source of a reset (WDT, BUTTON...)?
One again i have been searching and reading about the topic but i couldn't find clear and concise information, some people have some code at the forum they say "should" work but once again i don't want to break my board and i prefer to ask first.
Thank you very much for your help.