FileVault Encryption

Im thinking of setting up filevault on my macbook but i just have a few questions.

-Is it possible to set up filevault encryption on my whole home /dir with out having to format or change anything that is on it?

-Once filevault has been set up, is it possible to de-activate it afterwards with out loosing any information or having to format?

-As it encrypts and un-encrypts information on the fly, does this have a significant affect on the macbooks battery life?

-How does it work, do you just enter your password and log in and then never notice it?

-do any of you use it, what do you think of it, is it a pain?

Thanks.

I have not used it but know that the intitial encryption takes a while

No reformatting is required, but you will need free space on your mac that is larger than your home folder, for filevault to use as temp files while the initial encryption is done

You can turn it off, and after is does all the unencryption your home folder is back as usual

How much data do you really want to encrypt, if is just a couple of folders that really need it, consider an encrypted disk image instead

i already have truecrypt, it would be nice just to have that security on my macbook if it ever got stolen, i dont really have anything that valuable on my macbook.

While I have not used Filevault, I've heard of enough problems created by it to avoid it. I'd stick to third parts apps and encrypt only the folders you need to. I keep GPGFile Tool on my dock and just drag and drop what ever I need. When I double click my encrypted files, it pops up and requests my password. Very handy