First, the word you are looking for is 'touring', 'tourism' has different implications.
Second, interstates are generally closed to bicycles and unpleasant to ride on anyway. For example, I-84 is open to bicycles along the Columbia, but to my knowledge, I-5 is only open to them in a short stretch on the Cali/Oregon border where no alternative exists.
Depending on where you want to go, you can buy detailed maps which tell you where to find water, campgrounds, hostels, grocery stores, etc, or just use standard state maps with some success. Adventure Cycling makes such nice maps, but you may or may not want to spend money on them. It's worth checking out their website.
Given that you live in the South, water can be an issue. You'll want a fairly large carrying capacity of water so that you don't run out between sources. I carry ~4 L and refill around once a day in the cooler, wetter climates of the pacific northwest.
As far as the bike goes, it's possible to use just about anything. I've personally enjoyed having a triple crankset, but your 10-speed should be fine if you travel light or don't ride in the mountains. I think I would have died without my granny gear on one day where I rode uphill over ~25 miles gaining almost 7000'.
You can also see
>>121980 for some tips I gave in another thread.
