I personally prefer the short-handed tables to avoid the limpers as much as possible. I never seem to do as well at the larger tables because of the guy playing the 8/3os catching his hand. I like to play the .50/$1 and $1/$2 (that's the level I'm comfortable with now) as I find that anything lower than these (micro-limits) are filled with noobs, and play is just atrocious. To answer your specific questions:
Pre-flop: Do you play more aggressively pre-flop short-handed than at a full table? No, not really. Now, once I get a feel for the players at the table, then I might, if I find that they are really tight. But again, it can be difficult to bluff on limit tables.
How do you reason when you have overcards and are first to speak? How about on the button when no one's bet? First-to-speak: I'll check it down, so as not to give an opponent the chance to raise me. This way I can hopefully see the next card for a cheaper price. On-the-button, I would definitely bet here.
Is your decision whether to slowplay a monster affected by the table size? I think slow playing at limit is a mistake, unless you flop the nuts. Then I would slow play at first, to try to get a bet to raise. Table size wouldn't matter. But on a larger table, definitely no slow playing.
How about semibluffing draws? Depends on my feel of the table, but I would consider doing it more on a 6-player that a 10.
Do you see any reasons to play the turn or the river differently?
If I've flopped the nuts, perhaps. I might try a little check/raise action. Or, if it's a hand that has been checked-down continually, I may take a stab at the pot.