If it's a level change, heading change (for weather, etc), or a route request, just ask for it. In the unlikely event that I have higher priority tasks, I will ask you to standby or will have already imposed radio silence. Increasing RT workload by pre-empting run of the mill pilot requests with a 'request' for a request is crazy.
On the 2nd part of the post,you can either use 'Say again' or ask me to confirm cleared level, heading or waypoint/route. I would rather we were both clear on the clearance issued in all circumstances, than leaving it to an assumption on both our parts.