tools of the trade

hello guys, i’m completely a newbie but i have patience and interest, i’m not looking for a tutorial, nor requesting someone to do what i’ve got in mind… i’m just asking wich tool (software) i need for some kind of editing-creation
http://imagizer.imageshack.us/v2/150x100q90/829/ytd7.jpg
i’ve decided to edit one of those models in order to get “mafia” bill, the 1st idea is to put the bill’s head on the mafia looking guy… then to attach the model of the hat… permanently on his head
so… is that possible? (i mean in the way i said, keeping the faceposing of bill) and EXACTLY which kind of software i should use?
http://imagizer.imageshack.us/v2/150x100q90/823/9fv3.jpg
in that different case i got those kids zombie and i want to get them back to life editing their 3d model (same question for bill… not how to but wich tools?)

sorry if the section isn’t correct or the topic isn’t nothing new but i really want to enjoy this part of gmod too and i don’t know how…

thank you

This is not the forum for model editing. Post in this forum.

thanks, and sorry for noobness… now mark me with shame :smiley: (and delete if you please)