In limit hold'em pot expressed odds are SUPER important because you can't stack someone hitting a 2 outer, you can only win a couple extra bets. If you're not being laid odds you simply don't play. As far as multitabling, the odds become second nature. I'll 16+ table, and think nothing of it. Just practice doing it, even if you're not in the hand. Figure out what the odds are, and if you'd be getting good odds or not.
A quick tip to make things easier. If you have 8 or more outs, you're almost ALWAYS getting odds in limit based up expressed+implied odds. So those are no-brainers. Same with most multiway pots that were bumped preflop. If you catch even one pair, and if you're live to your 2 pair/trips, then you're often getting more than the 8:1 you need to go on. Even if 3 people stuck for the flop for 2 bets, there's 6 in there, so if someone bets you're getting 7:1, and you don't think you'll get at least one double bet off them on the next 2 streets? Of course you will, so you should take the turn. Only when the pot is tiny and heads up might you not be able to continue on one of these draws.
For the rest, just practice them, and it'll come along.