When you shift to 4hi or 4lo, the transfer case begins to turn the front drive shaft. The front drive shaft is connected to the front differential. The stock front differential is an open design (no LSD). The front differential in turn (no pun intended) drives both front axles. The manual front hubs lock and unlock the front axle to each front wheel.

So, to answer your questions:

When in 4wd, with the hubs unlocked, is my front axle engaged at all? Yes.

If so, just one wheel? No, both wheels

I assume the front axle is not LSD. Actually the front differential is not LSD. But you have the general idea.

I hope my questions are not wearing out my welcome! That's how we learn things, by asking questions.