Ahhhh, yes, you are correct - i think the flight is more expensive for the tourists.
As for your itinerary, a good site for trekking in Nepal is:
I haven't visited the forum in a year or so, but they have some very knowledgable people on the forum. I can give you a hand with some stuff, but if you want specifics about weather that time of year, what will be open/closed that time of year, current prices, maoist situation, etc....they can definitely help.
Oh yeah, scrap the rain gear. If it rains, go inside, and by the time you are high enough, it will be snow. You're going to have a blast!