curved gear plate question

[JohnsLegos]

I was on Bricklink looking for a part and I think I found the part I need but have a couple of questions. The part I was looking at was a 24121 11x11 curved gear and what I was wondering is (1) can you put multiples of these together to make a complete circle and also (2) how big in diameter would it be (preferably in inches or feet I am not good at conversions..) and (3) is the gear drive only on the inside? Thanks for any help!

[Jurss]

Yes, You can make circle from 4 sections

It will be 21 studs in diameter, which will be around 168mm

Yes, gear only on inside