The hottest part of the smoker is the fire box, it can get upwards of 500-700° depending on the size of fire and type of fuel - think of a wood stove, same premis.
The main body is generally much cooler, usually you can place your hand on the main body for 10-15 seconds and not burn yourself, might get a little uncomfortable, but not scorch you hot.
I'm sure some folks will have some better detailed info for you, but that is the basics.
For bolts and hinges I would try to get 316 SS or better, the inside of the smoker gets seasoned to help protect it from rust, and the outside gets painted or powder coated, but the week links in the chain are the nuts and bolts. If you use 316 SS and some high temp anti-seize thread guard you will be able to repair things down the road a lot easier.
