I think you can use portal in gmod 10, but I'm not so sure.
No it is not. It requires one of the games in the half life 2 series such as TF2 portal or half life 2.
no. gmod is only for the pc.
No. Gmod is only for PC
You need to download Gmod 9.0.4c when you start there will be 3 choose unmark the Gmod 9.0.4b and your set to go and play gmod 9 online.
Gmod 10 is a pay game. It can be purchased from the Steam store at http://store.steampowered.com It costs $10
you click the shortcut icon er the gmod .exe/file!
go to steam.com here are some links related to Gmod to help you: Steam: http://store.steampowered.com/ Download stuff to Gmod here: http://www.garrysmod.org/downloads/ About Gmod: http://www.garrysmod.com/about/ Gmod fourums: http://www.facepunchstudios.com/
Any Source GamePreferably CS:S as most gmod users have this
piggymoo.com has all of stargate, but I'm not sure what gmod is.
gmod 9, yes gmod 10-no
steam/steamapps/username/gmod/gmod/data/adv_dup(or something like that)/* *place dupe .txt file or file folder with dups in it, here)