PAT16! That's so cool!!! Madagascar is so amazing and beautiful!!!
might be helpful to you in planning your trip. It's a wiki-type of website that has some information, though a lot more could be added to it, but it's a HUGE island.
Well PAT16 as for planning, it depends on what you want to do. What are you most interested in? Do you want to do a lot of hiking? What kind of geography and climate do you want to see? Dry? Rainforest? Beaches?
One way to get around more cheaply and easily is by bus by Cotisse Transport. They run a tight schedule and have newer, very clean buses, though I can't say that they exactly drive any safer than a lot of other drivers, but they sure do drive fast! This can be a good option because most of the other buses I've found only leave when they've found enough passengers, which can take hours. There's a whole page on Cotisse Transport at madacamp.com
All the best on your amazing travel!