High Point City Lake: HP limit of 10hp. You *can* launch a boat with a larger engine, you just can't run it. Often they will permit you to run it in order to trailer your boat if you don't do it full blast and make a mess. They do rent jonboats, and I think they rent trolling motors but you would want to call and ask about the motors. Jerry would know, also. You can certainly bring your own.
Oak Hollow: No restrictions, people run boats there of every size. They allow water skiing by permit which limits the number of skiers at any given time but they can be found there during summer.
Fishing can be good to very good at both lakes, depending on your knowledge of the lake. However, if you had no knowledge of the lakes, I think you'd be more likely to connect with fish and better fish at HPCL. Oak Hollow has some nice fish in it, but it can be a tough nut to crack during summer at least, since much of the better structure is offshore rocks and creek channel bends that are not easy to find.
I have heard the fishing at Oak Hollow is actually pretty decent during early to mid Spring, but I have never gone there... I'm usually at Randleman or HPCL during this time of year. Now would be a good time to start hitting HPCL for the chunky ones; the fish there are often shaped like footballs.
If you are going fishing at HPCL, feel free to PM me or give me your email address and I can try to help a bit with a few details. Jerry Condrey is the real expert at City Lake, however, and much of what I have learned has been from him and then the things I have figured out based on his starting tips.
For Spring at Oak Hollow, all I can say is what I've heard... start with the area by the golf course and work the different depths with cranks, shakey heads, and slow-rolling spinnerbaits, and then do the same on main lake and secondary points.