I know Lapa is the place to hang out at night in Rio. Are there any bars where one can meet escorts? Any streets, places outside ? 

Lapa is not the place where you should hang out at night. 

3 hours ago, likeohmygod said:

Lapa is not the place where you should hang out at night. 

Is this because there are no escorts in Lapa, or because it’s dangerous? 

Both.

Have a look at the forum...is fill of information. If you're new to Rio, stay the southern bairros.

17 yrs of experience in Brazil here and i 110% agree with Likeohmygod!  And yes to both your questions!

I've hung out at Lapa, at night, with a bunch of Brazilian friends, for two nights straight a few weeks ago. I can't see where you would find any escorts there but there are a lot of other stuff going on.  Lots of bars in the area with cool music, as well as the beers/food by the arches.

The crowd is young and mostly attractive (It's Brazil after all). You can definitely pick someone up here to enjoy later, if you so choose, as we did, after doing one's due diligence, of course.

Definitely not a super safe place to hang out, and I was advised to put my wallet in my front pocket and secure my cellphone in the front waistband of my pants, if not in the front pockets, and not use it as much when hanging out.  The beers were cheap and the company enjoyable, and made some new friends (mas falam Portugues). I was also advised to not wander too far from the crowd, so you have to be extra diligent in this place.

Tho I did have to use my cellphone to take these, at the Arches of Lapa (the Aqueduct):

 

I was advised to go to Lapa with a local if at all possible.  That is what I did the first time: ...went with Ernani who was a popular escort in Brazil as well as in parts of the States.  He came to my hotel on "his hog;" his handsome motorcycle:  I don't ride on the back of these, so he hired a taxi for me and led the way.  We spent about 3 hours just walking in the middle of the main streets amongst the throngs of people.  I did not particularly  have that much of a good time doing this, but it was great being able to go to this area on a Friday night, one of the best nights to go besides Saturday and to see what many folks raved about.  

In 2010 or maybe it was 2011, I again went to Lapa with two gringo amigos and a local carioca.  Unfortunately, the time that I had was NOT what I'd envisioned; I, more than likely will venture there again if I ever return to Rio, for it's a barrio that has character and a good vibe and is quite lively, but again, one has to be careful, not paranoid. 

Go with a local or locals on Fridays/Saturdays, and make the better of the experience.