With levels of Nirtites and Nitrates off the chart, water changes won't hurt your cycle. The bacteria is embedded in your filter media and in your substrate so it won't be bothered if you do water changes.
As for sites to look at fish... AC has a good data base if you want pictures. Last time I checked some of the bios were a little outdated. Also, Dr.Fosters and Smith have pictures. And there is one other site that I really like because people are able to give their personal experience is "the age of aquariums". However, the best thing to do when choosing a fish is to find a couple you like and ask around here for people who have had experience with them. That way, hopefully you won't have any surprises when you get them and you will find fish that are compatible with you and the other fish you want to add.