Tanzania - travel tips?

I´m planning for a trip to Tanzania and I have some questions:

When is the best time of year to go there(i.e. when it´s not too hot)?
What´s the aproximate cost for:

lodging and food (traveling on a low budget basis)?
Traveling whithin the country(by train or plane)?
Visiting National parks?
Visiting mount Kilimanjaro?

Grateful for any help

Best Times to Visit

Northern Tanzania
July through October; December through March

Southern Tanzania
June through October

Zanzibar, Pemba and Mafia
July through October; December through March

Western Tanzania
May through October

http://www.tanzania-web.com/home2.htm

I think this site will answer most of your questions.

I don’t want to put you off your visit, Gottfrid, but I think you should be aware of this public safety report issued by the UK Foreign Office following recent developments in the risk of terrorist attacks.

UK issues Zanzibar terror warning.

Lots of information here as well.