Reviving:Thanks for replying Brian. I REALLY like the idea of having the last unit in the battalion go 'Unconscious' and have to be taken back to your Home City or a friendly NPC Town to get the possibility of reviving for Crowns. That would let a player decide whether to revive or drop them at some later time, as well as an interesting idea for a 'Hospital' building to store wounded units (otherwise they'll clutter up an army and be literally dead weight) - which in turn could be a building that either revives one unit at a time VERY slowly (hours or days depending on how leveled/important it is) or can be instantly healed with that Crown system. But that's speculation onto other matters really.
I think that the Crown cost for reviving units should depend on both level and unit type. For instance, a cheap Maceman and a Royal Dragon shouldn't both be 10 Crowns to revive if both are the same level. I think each unit should have a different scaling cost associated with it, whereas a Maceman may scale at .5 Crowns per level (10crowns/lvl20), a Mounted Knight at say ~1.0 (20crowns/lvl20), and a Royal Dragon at 1.5 (30crowns/lvl20). Or some scaling system like that depending on how valuable that particular unit type already is. That would make the most sense to me instead of seeing a Maceman and a Dragon scaling the same to revive. In the end there are multiple ways to fiddle with the details, but I do believe many players would want the option of reviving units available to them, and are willing to expend Crowns to get it.
Battle Rewards: What normally happens in at least my battles that start to turn south is I retreat at a lower cost once a lot of my army has been hurt or killed to avoid further losses, thus lose out on getting any reward. If you have to stay the whole fight and lose more than half your army to get a little 1/2 Crown reward, I can't see it being worth it. But if you have a certain point in the battle (be it time, army strength reduction %, or whatever) whereas a player could retreat and still get the Crown reward, that may be nice. I would suggest it being an overall army health reduction or whatever the current surrender system relies on instead of time to avoid players entering fights, running uncatchably around the map for 10 minutes, then retreating for their little reward. The decision-making device should ensure a fight has actually occurred before letting the loser get their pittance.
Varied PvP: I like those ideas, though my only qualm with them may be that if the player hasn't made those armies, they won't feel very connected at all with them (= not as fun). I think they would be great options for more PvP for sure - but more PvP options for a player-built army would be even more fun for players I think. Then they feel directly invested in the outcomes, and with a Revive option for those invested armies a player wont be terrified to use them in these new PvP avenues. But both player and not-player army control would be great additions to the current limited PvP. The defense idea against NPC/Player army attacks as you suggested would be delightful in my opinion.