Is this an accurate pot odds calculation?
$60 (Hero) + $60 (Villian) + $10 (Small Blind) = $130
$140 (Flop Bet x2) + $130 (Preflop Pot) = $270
$140 (Hero Bet) + $340 (Villian Reraise) + $270 (Flop Pot) = $750
Yep, looks good to me. Your math is correct, although I got $750 instead of $760. This results in odds slightly better than the 3:1 you mentioned.
$750:$200 = 3.75:1
Before I answer the rest of your questions I'd like to point out something on the turn. You say you checked behind because you "smelled a flush." Consider this: your hand is dead against a flush. You are never going to win this hand when your opponent has a flush, unless Villian is a nit and you can push him off a baby flush (which is never going to happen).
The important point to realize here is that completed flushes are only a small part of your opponents range. When you check the turn simply because a small percentage of his range now holds the nuts versus your hand you allow the rest of his range to realize free equity. There are a fair amount of river cards that will help his range immensely versus your hand.
This is a perfect case of when you need to bet/fold. You have a hand strong enough to bet for value and you also want to protect your hand against one card flush draws, straight draws, and so on, but you don't have a hand strong enough to continue versus a reraise. Think about it. Any hand reraising your turn bet likely has your KQ beat.
So on the turn, bet $150-$160 or so into the $270 pot. If he calls, his range is capped. Any strong made hand on the turn would be reraising you for protection and value, so you have a strong read in this scenario. His range largely consists of one card spade flush draws, straight draws, weaker pairs, etc., as well as the occasional slowplayed flush. If everything bricks on the river you can make a small value bet and hope he calls down. If straights/flushes complete, you can check/fold depending on his bet sizing.
Anyways, enough ranting, on to your questions.
Hero calls - was this the right decision to make?
No. Not at all. This is a very strong line for Villian to take. Try to consider what the population tendencies are here. Yes, you are getting good pot odds but pot odds really go out of the window when your opponent makes such a small reraise and the board is this wet. There's a fair amount of possible straights on board as well as three spades. People don't often bluff boards like these and when they do they'll bet bigger. Such a small bet screams value. And there are a fair amount of legitimate hands that he could have here which are beating you:
Straights: KJ/J8 make perfect sense if he had a backdoor spade draw to go with it.
Two-Pairs: T9, 97, and even Q9
Regardless, his line just screams completed flush. Small reraises or check-raises on the turn/river are fairly strong indicators of strength from fish. As such, you just have to fold here. When you call and you're right, you profit a small amount. When you call and you're wrong, you lose a ton.
Two tight folds are far better than two loose calls.
Is it possible to distinguish between a slow-play and a bluff with Villain's play (check on the turn and raise on the river)?
I think I answered this question fully with my response to the second question. This is just so rarely going to be a bluff. Recreational players just do not bluff boards like these and you know you're playing recreational players. It's a $1.50 9-man SNG. You shouldn't be bluffcatching at the micros. It's always a slowplay or rivered two-pair/straight. Thinking through the hand while keeping ranges in mind, combined with experience regarding population tendencies, will help a ton in making decisions in spots like these.
And like I said, small reraises on the turn/river are huge, huge indicators of strength.