You got picsReturns, I went with 1" slip outside of the tank in order to use street 90's for a lower profile to the wall and 1" threaded inside the tank that immediately splits to two 1/2" loclines.
Overflow, both sides 1" slip so that I didn't have to worry about adjusting the bh if the threads didn't align in the direction the pipe was headed. Glued on the outside, press fit inside the overflow.

but def do the herbie's

