As Carl noted, you can only adjust the CLASS with the key on ACC.
The biggest problem with these units is cold solder joints on the circuit board. You can pull the unit apart and look at the solder joints and usually see one that looks different. Use a small solder gun, like one of the pencil ones and let it get real hot and touch the joints. You may want to put a little solder on the point first. You want to make sure the tip is real hot as you do not want to stay on the solder point very long. This is a fairly common problem with these old bikes.
As far as the bump, the best fix on that is to install a set of Progressive springs. I'm sure your old springs are worn out. You may also be low on shock oil.
I have to say that I admire your enthusiasm, but it would scare me to take off on any bike without knowing any more than you do about this bike. I would at least change out all the fluids, check the brakes, look at how old the tires are and are they properly inflated, does the bike still have the old fuse block?
I have 164,000 miles on my 83 and know it pretty good inside out and would still do a good going over before I would take off on a trip and always carry a lot of tools with me.
Good luck on your trip and keep us posted.
RandyA