Hi there bobcat. Congratulations on your return to cycling. 40 miles is a pretty respectable distance on any bike, so well done.
I won't offer any advice on bike style, but I can address any gearhub questions.
The first thing I would ask is if you find yourself needing both higher and lower gears (ie more range) or do you just need the high end adjusted up, or the low end adjusted down. If the latter is the case, the change can be accomplished quickly and inexpensively by changing the chainring/cog ratio.
If you find you need more range in the gears, (both a lower low and a higher high), then it follows that a hub with more gears (8 is a good number) would be more suitable.
Retrofitting gearhubs is not rocket science, but it does seem to be beyond the capabilities of some bike shops, as does the maintenance and repair of said units, so before assigning the task, try to get a feel for the competence level of your shop mechanics.
As always, if you tell us where you are located, someone may be able to direct you to someone local that has a reputation.
EDIT: Reading through the rest of the thread, it seems your bike is not really a good fit anyway, so going to the expense of a drive train renovation would probably not be worth while.