i did measure a single 328 running think it was about 15ma if i remember
That's about right. I usually use 20ma as the practical upper limit.
As to regulators, if you are only power the mcu, you may think if a) you need a regulator; and b) you need a beefy one.
A 78L05 would be a good choice here, or the 1117s - they are much cheaper.