Context: Either in late August or early September I'm planning to go up there to visit some friends, possibly meet up with a girl that I met off of tinder & I'm now chatting with on Instagram, and of course experience New York City.
Last time I was up there it was for my high school senior trip and I only got to experience the generic "tourist stuff" in a span of 3 days.
This time I plan on getting more into the "nitty gritty". Hopefully for an entire week and possibly 2 weeks if I arrange a "working vacation" with my job. So long as I have a high speed internet connection I can do most of what my job demands of me.
I'm going to be most likely basing out of Brooklyn since I have a friend from college who lives there with his gf. Also, the girl from tinder lives there as well.

Questions:1. If I'm going to be staying for a week or possibly two weeks would it be good to get an Airbnb instead of mooching off my friend and sleeping on his couch for 7 to 14 days? We're friends but we aren't besties. Also, maybe I'll get lucky and that tinder girl will let me live with her (I
HIGHLY doubt that. Especially this early in our "correspondence". Nice to think about though...

)
2. Is there a relatively easy way to get from Brooklyn to Manhattan and back again? I assume the subway but that's kinda dependent on where I'm actually staying in Brooklyn. Also, I assume I could get a "weekly" metro card while I'm there?
I'll think of more questions once more details start to come to light.
Also, feel free to fill me in on any neat stuff that I should experience while I'm there. Anything that's art, design, music, and food related I'm definitely down for.