Stripslashes Help

[KittHaven]

Hello! I know that I've asked this before, and I know I've been HELPED before, but it's frustrating searching for it. I cannot find it and I've tried doing it myself but I'm failing miserably!

How do you enter the stripslashes command into certain places? I've managed to do the user bio as I found Kyttias' post from before but I cannot find anywhere else. The places I want to input it are:

Bio's (done)
Visitor messages
PM's (not sure if this is a problem, yet, but just in case)
Both item and adopt shops

And anywhere else people have noticed problems..... thanks for the help. Sorry I couldn't find it myself! If someone helps me I'm bookmarking this page!!!!! >.<

Also, how do you stop people signing up with apostrophes in their name? I want to make it so that they need to use letters a-z or 0-9. I have no members on the site at the moment, while I sort things out, and would like to stop that happening before it does like last time!! XD

Thanks for all your help