Hi Duck,
Welcome to the forum. It makes a refreshing change to see a newcomer who wants to make a genuine post

Flop:
I hate the idea of building this pot on the flop. There's no way to protect my hand, and if I bet out and get a raise and a few callers the pot is huge. I elect to C/C and see how the passive players react on the turn.
I think you should have bet the flop. You'll usually still be ahead, you were the last aggressor preflop and you're against opponents who will cold call with a wide range and pay you off with such. Even if you put the UTG raiser on 10% you're still ahead of most of his range. You're not betting to protect your hand, you're betting for value imo.
For example, let's give him a range of {77+, ATs+, AJ+, KJs+, KQ, QJs, JTs}. That's a little less than 10%.
Remembering that the

and

are accounted for, we can look at how many hands he's likely to continue with that you're ahead of. I'm going to assume that he won't have a set because KK, JJ and TT would probably have capped preflop. I'll also assume he doesn't have QQ for the same reason.
Hands that are beating you:
Straight with AQ: 8 combos
Two pair with KJs or JTs: 4 combos
Hands you're beating:
Top pair with AK or KQ: 18 combos
Middle pair with AJ or QJs: 9 combos
Weak pair with 77, 88, 99 or AT: 24 combos
(Some of these also have a gutshot or oesd, etc.)
Hands you're splitting with:
The other two aces: 1 combo
You might question whether you'll get called by hands like 77 on this flop. Well, you might not. But then again, loose passive players like to call, particularly on the flop.
If you include the big pairs in his range (TT-KK) then the numbers are closer, but I think these are unlikely given the preflop action. It looks like a pretty clear value bet on the flop to me.
Turn:
Safe card, but I'm still worried about player's 1 range, since at the time I have a low PFR for him. I C/C
I really don't like this. If you're going to check the flop to wait for a safe turn card, you have to get some value on the turn imo. The problem is that you're against a passive opponent who may not bet for you to check-raise. Donking the turn is an option if you're unsure whether he'll bet.
River:
Considered betting out, but I have him tagged as somewhat loose passive/ so I C/C again and just go to showdown.
This doesn't really make sense. If he's passive he'll often check behind even with a hand he should be value betting, so checking to him can't be right if it's value you're after.
I think you're considering betting out because you think you might still be ahead, and you're worried you might be missing some value? Am I right?
The fact that you're worried about this on the river I think shows that you probably played the hand too passively on the earlier streets.
Anyway, good to have you here, and good luck in the freeroll.