mnn new tank.
Basically, find anyone you know that has a healthy tank, and borrow their filter sponges for a 10 minutes. Clean them in your tank (after letting it settle for 24 hours, as that will build up bacteria.
Dainos are hardy little fish (I got mine when i bought some plants, we had to catch them by dropping the water level in the tank (substantially), and they are none the worse for wear. About the black widow tetras, i'd agree with them being nippy little buggers, i've got two females, the smaller one of the two has nipped a rather large mark in the tail of the other.
Angels are great, my mate has 3 of them, and they are highly inquisitive. They play follow the finger game - Put your finger against the glass and move it up and down. Fish go upppp, fish go dowwwn.
You can supposedly cycle a tank using ammonia, but... Confusing
If you can, find some decorations that have large holes in them, your Danios will love them
Try and get some driftwood as well for the bristlenoses.
And, most importantly, bug everyone you can for ideas on fishies. You will get varying answers, so use google. It is your friend.