Yes any other XPS than XPS 17 can be charger via TB dock with no issues.  But they are putting these RTX Cards in XPS 17 so no way a dock can supply enough power through Type C or TB.  Yes you can have both dock and power cable connected with no issues.   
The answer to this post [URL]#M87189 seems to answer my question, but I'm considering getting the Caldigit Element Hub (Thunderbolt 4) to use with my (being built) XPS 17 9710. The hub will supply up to 60 watts of charging, and of course the power supply that comes with the laptop supplies 130 watts. The post cited above seems to imply there's no problem leaving both the hub and the power supply connected, which I would suspect anyway, but I'd like to be a little more confident.    
Simultaneous Power Supply and Dock Connection