1) absolutely - pretty straightforward for even a basic FDM 3d printer.

2) painting it yourself would be the cheaper opyion. But there are a lot of full colour machines around now, including fdm ones. So yep, it can definotely be made full colour.

3) ideally you'd want it made on a polyjet priunter. Thius is a machine the uses coloured 'binder' in much the same way a normal inkjet printers does. The difference is that it prints on really fine powder that is bound into a solid block.
These machines cost upwards of $150,000 - and most of the decent sized print bureaus will have them.

The only way to find out what it will cost is to upload a similiar model - you'll probably need to have the final file in an AMF format.
Presumably there is a plugin for autocad that should export to amf format.
I;d be surprised if there wasn't.

It will also need to be a 'solid' file. Not just 'faces'.

Best way to get a ball park cost is to upload to shapeways. https://www.shapeways.com/