Hi Chad,
Do some searches here on Permies...much of this has already been covered...
living in a green house
1. Will the humidity destroy my all aluminum bus?
Yes it can, and other metals as well...
2. My bus is over twelve feet tall, so with a shed style roof the peak would be over twenty feet tall if I run a steep pitch. How flat can the pitch of my roof be if I should choose to use sliding patio door glass?
This is structurally a challenging concept with more simpler ones available.
3. Because of the location I have to work with, the shed style roof slants away from the sun. Is it worth bothering to fit patio glass instead of corrugated polycarbonate panels since the sun is going to be reflecting off of the roof so much anyway?
I think reading the above may address this...?
4. Will the patio doors be a LOT better at retaining heat than the corrugated polycarbonate panels?
No...
5. Would be twinwall polycarbonate be a worthwhile expenditure? ( I live on vancouver island, pacific northwest)
If you are building a greenhouse garage...yes...but in all I am not clear why doing this seems like a good idea.
Regards,
j