1. Is there any free downloadable demo of this game up on the net?

2. Is there a tutorial built into the game?

3. Can you turn off certain aspects of complexity? For example, are you forced to
do all of the tasks (gunner, driver, etc) or is there AI?

4. Can you just plain turn off things that are much too difficult, such as the gearbox,
and treat the tank as if it had automatic transmission?

1 - not sure, there was demo at one point available, but it was based on very early version of the game anyway

2 - no, in CD version there was text document, which described pretty much everything the beginner should know. I suppose that GOG version will include it as well...

3 - You don't have to do everything. You can if you want - but you don't have to.

4 - YES! Actually, this is one of the best features of this game, fine tuning of difficulty is one of its best aspects.

for reasons, the demo has never been rereleased.