yes, go! free food and dring, + sacrifice now and she will do the same in return in the future.
ok, depends on the girl, but it should be hha
Go under the pretense of just giving her a life to the BBQ, if it looks like the type of people who might want to get to know then stay. If not just drop her off "because you have some other activity that was planned prior to the BBQ invitation".
You're setting a precedent. Just sayin'.
dont worry abt it too much, you know at some point you will hang out witht hem socially anyway.. just because they are her friends doesnt mean you wont get along with them and maybe some of them will be youre friends too. this kind of thing only will make you and her have mroe thigns in common.
You should go, meet her friends and know them all if you are serious about your gf.