I wouldn't worry too much about it, and I think in general there is too much emphasis placed on pH.
Unless you are trying to breed some pretty picky fish, most critters will probably do okay as long as the water is relatively stable.
Some of the guides for MTS and such recommend putting a bit of dolomite on the very bottom, I think it's to help keep the substrate from being too acidic, while providing some Mg and Ca.
It kinda depends on your water, if you have fairly hard water, you probably don't need to worry about it, as regular water changes will bring in a certain amount of minerals. If you water is pretty soft, you might want a bit.
Dirted tanks are a bit 'rough', and are hard to get to adhere to really precise parameters. At the same time, they can work really well for a lot of people, especially if you take a bit more 'hands-off' type approach. If you aren't set on a specific fish/plant combo, it would probably work best to just set up your tank, plant it with a bit of a variety, and do a fishless cycle. Once the cycle is complete, do a couple water tests, and then pick fish that work well in those ranges.