I have super hard water, and I have found it is easiest to just live with it. If things are going wrong in your tank, a water change (or series of them) is often one of the best places to start to get things right again. If you just live with what you have, that water change is going to be so much easier!
My pH is 8.3, GH and KH are in the mid 20's. A huge piece of driftwood has no measurable effect on my water parameters, although it does yellow the water some and the fish seem to like it. I've found that fish such as African rift lake cichlids thrive in my water (no surprise there) and breed to the point of being a nuisance. And most other fish do just fine. A few years ago I tried Cardinal tetras, a species I have avoided for their reputation of being a bit delicate and needing soft acid water. Over a few years time I lost 1 fish out of the 5 I originally purchased. So I tripled my school of them. The second batch is doing just as well.
Unless you are trying to breed finicky wild species, most of what is available in the pet store will do fine in hard alkaline water. Just keep it clean and they are likely to thrive.
On the other hand, I have pretty much failed at plants... So if you are trying to do plants, I have no advice!
As far as chemistry is concerned, you will always have to cut your tap with distilled water to keep your altered parameters. If you do every water change with tap, eventually you will make your way back to the tap water parameters.
wren