fits a 3/8 in drill but if mixing a lot would recommend a 1/2 in drill for the extra power.
I’d say the diameter is about 3” wide
Yes. It's very sturdy.
Sure, if it all you already had but I wouldn't buy it for that purpose. They make others that would do a better and more efficient job
Only if you are very patient.
I wouldn't, it's on the small side especially if your mixing the whole bag. If you're only mixing in small amounts it might be good