What type of amplifier should I plug an Ozark resonator guitar into?

There is something of a difference in opinion with this one between whether a small, clean valve combo or an acoustic amp is better. The acoustic amp will give you more of your resonator's 'true' sound (which is a matter of opinion and taste of course) but many classic resonator tones are achieved by using an amp like a Fender Blues Junior. Both will give different results and both are correct for different reasons. For our money, we'd go with the electric valve combo.

Do I need special strings for an Ozark resonator?

No, regular acoustic strings are fine, the heavier the better! Special 'resophonic' strings are available from various manufacturers but those are a preference, not a necessity.

What notes are resonator guitars tuned to?

Traditionally, resonators are tuned to Open D, Open G and DADGAD tunings in order to facilitate harmonic overtones when playing with a slide. However, there are no rules written down saying what you can and can't do - plenty of people also use these in Standard tuning so just go with what works for you!