Is there a decent way to rehydrate and sauté dried chili peppers?
Frankly drying is not the way to go if you want to retain flavor and texture. When you dry fruit (chilis are fruits, not vegetables) you make a load of irreversible changes in texture and flavor. A chili is made of tiny cells filled with liquid, the drying process ruptures these so the water can escape. Rehydrating a dried chili doesn't make it plump up again, really you get more of a soggy mess. 

Flavor-wise you'll lose some of that chili essence, the non heat flavor. Heat-wise you'll retain the spice, if anything it gets more concentrated. 

You can steam peppers, it's a good way to cook them without losing flavor, and no the steam won't carry flavor away. It won't concentrate the chili flavor though or make them spicier somehow. 

Growing your own really spicy chilis can be done, depending on the climate you may need a greenhouse. 

If heat is your goal your best bet is to shop around for the spiciest peppers you can and then eat them raw rather than cooking them first, or turn them into a hot sauce. Include the seeds and the pith if you really want to feel it. If you can't find them fresh often then freeze them, they keep for years if they're sealed up properly, and although their texture isn't as good as fresh it's the closest you'll get.