Dave, how much dive experience do you have? It sounds like you're pretty new to the sport. I'm sure all this stuff could easily be sorted out in person with an experienced diver/mentor or a good instructor. It's pretty difficult for us to help you over the Internet.
The horizontal trim issue gets solved with experience, proper body positioning, attention to detail, and the appropriate distribution of weight.
If you are still a tad leg heavy, then you can always shift weight toward your head a smidge. One way of doing this is sliding the tank up a little. Arm/leg/foot/head positioning can also make a big difference.
I've encountered some beginners who have had an issue with rolling left or right underwater. After making sure that the BC is properly adjusted and the tank anchored securely to their back, it really just came down to an issue of balance. With experience and no further equipment changes, the rolling instability magically disappeared.
Hope this info helps...