1. Standard practice for us when departing home base London City Airport on our E170/190's. APU shutdown before leaving stand and packs are automatically commanded off when t/o thrust is set. Imput by MCDU.
2. Couple hunderd kilo's.
3. Reversers are pretty useless for our operation. Just lot's of noise and vibration. SOP for us is to always use idle reverse and let the carbon brakes do the braking. Even at MLAW into LCY. They need to be replaced every x months so better wear them down as you're paying for it anyway. Obviously can/will be used whenever conditions require so. (RTO etc)
4. SOP is to use full reverse on BOTH engines during RTO, even with one on fire. Wether or not you would want to do it personally is another question but assurance by manufacturer that it's the better option.