I was in your spot this time last year. It's vary exciting isn't it? (and it can get addicting vary fast) I got 4 d.tinctorius matechos for my first frogs i got a group hopping that I would get a breeding pair witch i did and just got my first eggs. I love the tinctorius's because they are big bold frogs you look in the tank and they are always out so that was a huge plus. I wouldn't go with The smaller frogs like the thumbnails size ones because of the size.. They are beautiful but i don't know they don't do anything for me I like to be able to see my frogs you know? Just do your homework and read up before you do anything so you know what your diveing into that's what I did and everything went great
As for ventilation like don said some people do the whole fan things I wouldn't worry about it for your first tank keep it simple!
Good luck!!!,
cameron