There are actually a fair number of species profiles and care sheets for less common species if you know where to look for them. In addition to a lot of useful information in English language books like Spawls et al. (2002), Necas (2004), Glaw & Vences (2007) and Tilbury (2010), there are a number of German language books with a lot of information in them as well. Some of these are even available online (example: Henkel, F. W. & Heinecke, S. 1996. Chamäleons im Terrarium:
http://en.bookfi.org/book/1555342). There are also many online sources and while many are in German or in other languages, if you put the URL into Google Translate, it will do its best and give you a better idea of what the articles are saying. Here are a few links to where you can find some of these care sheets:
Chameleons! Online E-Zine - Article Reference Page
ADCHAM - Web Archive
Chamaeleons Online - Wiki Page
IG-Chamäleons
AG Chamäleons - Journal Downloads
Specifically for
Trioceros johnstoni, for instance, ADCHAM has a profile (
ADCHAM T. johnstoni profile), Chamaeleons Online has a write up as well (
Chamaeleons Online T. johnstoni profile) and there is an article in one of the AG Chamäleons journal volumes (
AG Chamäleons - Volume 27).
As far as pursuing biology goes, for your undergraduate studies (Bachelor's degree), chances are you will major in Biology or Zoology, or some similar, relatively broad biological discipling. You may also have a similarly broad specialization (Marine Bio, Ecology, etc.) and you might be able to take some specialized courses, but the education you'll receive overall is going to be fairly broad and would enable you to pursue a lot of options after the fact. You really won't be able to specialize in herpetology, for instance, at this level. To be honest, most "herpetologists" are actually trained in broader fields (ecology, evolution, functional morphology, etc.) and then simply use reptiles and amphibians as their study organism.
A Bachelor's degree is really the first big step you'll probably need to make, and as has been mentioned, your long term interests may evolve during the process and put you on the right track. At some point during your training, however, you'll probably want to decide what type of work you want to do so that you can determine how much education and what degrees you will need. If you want to work at a zoo, teach high school biology, or something like that, for instance, you will need far less schooling than if you want to teach university level biology, conduct your own research, etc., and it may not be worth going through the entire process if it isn't what you want to do. There are a number of sectors, however, that you could end up working in that have positions for a wide range of qualification levels (from field/lab technicians working on assigned projects up to senior scientist with your own research programs). Ultimately with time, as you go through your education and talk to your advisors, you'll start to get an idea for what you are interested in doing.
Chris