hmm tose are hard questions but il do my best to answer them.
First to resize ur sig pic is to go to photo editer program i.e photoshop,gimp,photo explosion things like that and go to resize and srink it down. if u dont have one of those programs then pm it to me and ill do it
second u cant delete posts but u can edit them, go to the post that u wanna edit and look near the bottom of ur post and it should say edit. click that and change what u had typed.