1. Isn't terribly unusual unless you are comfortable switching in more apps that modify the UI (take your time and don't rush it...Froyo will be out in a few weeks and will help fix this anyways)
2) Lockups are NOT common on this phone, so either there is something that could be fixed (removing of certain apps or widgets perhaps) or else it needs a factory reset or to be looked at.
3) I can't speak to the coverage in your area. Have you dialed *228 (chose to program the coverage, not to try and activate your phone) to see if that helps? While some people have had problems with wireless network connections (not I happily) the 3G signal on the DX is generally pretty good. Also, convievably Verizon could be having a problem in your area, although the timing sounds suspicious.
Anyways, make sure your phone is in proper working order, and the lag and stutters should go away soon enough.