The answer is yes, of course. Just like gay men and women can be friends with one another and gay men can be friends with gay men and gay women friends with gay women.
Yes. As a straight man, I have a few female friends (though we've been friends since the 8th grade). I don't really have that many female friends aside from them, but since I grew up with them and attended college with them, we have remained close. Most of the friends I have now are males, but I really don't try to hang around too much with people because I'm a very busy person now.
Yes. There's obviously the gay male/straight female friendship but even straight guys/straight girls can be friends with each other and if you don't think so then you're probably still a teenager. Two adults of the opposite sex are totally capable of being friends with each other without it leading to sex because they have self control or they're just plain not attracted to each other or they're already in a happy relationship and aren't looking for anybody else. I have many straight guy friends who are in long term relationships and they're happy with their girlfriend so we don't have problems in getting along.
