Why don't you just invite her over to your place and see what she says? You could also do something nearby where you live and then go back to your place.

Just start a conversation to build comfort and some commonality. You went to the same school. Ask her "You went to insert school name?" and get a conversation rolling then you can switch topics.

Women will always wait for the man to make the first move. You have to take the lead and make it happen. Women also don't want to think when texting a guy; you have to make it as easy as possible for her. Think of it this way, if you had SO MANY matches and messages on dating apps/texts that it gets overwhelming and you don't have time to think/plan while also working or studying, wouldn't you just want somebody to take the lead and make it easier for you? Btw, I am a woman.

Set up the second date, don't wait.

"I suck dick for a living too" - hahahahaha omg. I wonder what you responded to that.

I know this chick sounds boring as hell, but maybe you could have still tried to get to meet her by saying you prefer to ask her questions/get to know her in person. Maybe you just weren't that attracted to her.

Why are you mad about the exclamation mark and then randomly say stop texting me?
I am a latina woman and we usually put an exclamation point to show enthusiasm/excitement. We tend to be very happy, friendly, and feminine.

Of course this is 100% investment! This means they are into you :)

Always in person. You could bring it up in a natural way saying something like "saw one of my ex's randomly and it was awkward. that ever happen to you? ____her response___do you have a good relationship with your ex's or keep in touch?" and you can just go from there. Honestly I wouldn't think anything of it. If you want to make her your gf what are you waiting for, just make it happen when you next see each other.

She said she has roommates and wants to go to your place. Anything wrong with going to your place? She definitely wants to make this happen from the texting. Just make your place happen.

Are you interested in her becoming your gf? I wouldn't think much about it because some people still remain on good terms with their ex and it doesn't mean anything. As for him having her on the profile picture it could be that he just hasn't updated it. If you are still curious as to why you could always just ask her