You'll like them for sure. The Sumatran Short Tails (black bloods) generally stay smaller, though I have an ~20 lb almost 6 foot female. I definitely keep mine on the leaner side - not underweight, just leaner. My biggest blood is about 6'4" and 25 lbs. If I fed her as much as she wanted, she'd easily be over 30 lbs.

Rats are fine. I do vary meal sizes. Sometimes they get one, sometimes two, sometimes larges, sometimes jumbos - sometimes there's a couple weeks and occasionally even longer between meals, especially in the winter. As for handling, I have a bad back and it can be a little tough for me sometimes pulling them out of the cages initially. Besides that, I'm fine. You'll be okay.