Excellent questions to ask. You might consider asking about manuevering at slow speeds and altitudes on departure. At a few airports we are asked to make tight turns shortly after departure, and our airspeed, or lack of it affects our turn rate/radius. Ask them to show you how to program the FMS for arrival/approach changes. Ask how wx affects the aircraft, ie anti ice robbing power from the engines. Ask about special departure procedures for an engine failure. If you are not already familier with them, they are proceedures that guarantee us to avoid terrain on a single motor. At SLC our proceedure has us turn left 320 off 34R right into traffic off of 34L. Your hands will be full getting traffic out of our way as we do something that may not even be close to the DP, and might in fact be a confliction with other traffic.
A bit more of a center thing but ask how important they consider ride reports on the route ahead, while somewhat for pax comfort, we don't want to hurt the FA's in the back. We can sit them down if it can't be avoided, but we have to know about it. Ask about wake turbulance avoidence techniques for the commuters/regionals. Ask about going down/slowing down at the same time, it can be done to a certain degree, alot of guys don't like to pop the boards for ATC, but the capability is there.
I agree with you, 5 minutes is a long time to slow. Our general rule is 1nm/10kts reduction in level flight, from our profile speed of 320 to slow to 250 takes 7 miles
Keep asking questions, the more you know about how we operate, the better off we all are.