The Question:

It won't last, but go for it if you can learn something and get something out of it. Sounds like that is what she wants out of it.

Bros before hoes but chicks before dicks...

I doesn't seem to me like it would hurt your friend ship since you said she already hooked up with another friend of your after "guy #1" right? So unless that upset him, your hooking up shouldn't bother him.

Just don't expect a long term relationship. This sounds like a doomed situation but w/e if it is just a booty call.

I think I ask an important question when I ask: How much do you really like this girl? To us, she is either vengeful or a skankaroo, (a girl that jumps from bed to bed, like a kangaroo) but to you she may be something else. You may just want a short-term relationship, and if you do, then go for it. But as a fellow Fakker, I have to suggest you get to know this girl more. Or get to know other girls more. Up to you, man.

I'd say bro's before hoes anytime. Depending on how close you are to the bro's involved ofc.
It can get kinda weird dating a pal's ex, and it feels weird having it done to you. No matter if you dislike/don't really care about your ex anymore. Especially hanging out all at the same time.

But if you can trust that your friend won't get hurt my you dating. I'd say go for it.

This. Don't ever expect a very fulfilling relationship out of someone who is not only in love with someone else, but that you're not even sure of how much you like her.

If you just want get some relationship experience, then go for it. But all that said, no one knows your exact situation, so it's up to you in the end.

It's also weird to ever date someone a friend of yours dated. Afterthought.