Calling is much better than 3betting as if we get 4 bet, we'll have to fold.

The only thing I would do differntly is raise the flop to get stacks in as the board is semi-drawy and some there's some bad turn cards for us.

This line is fine but you should honestly just call flop, call turn and call/go all in on river. We do not want to ever scare villain off a one pair hand.

I'm raising this flop for value right away. Four way makes things much more dangerous and there's a few turn cards giving new draws which we want to protect against.

99 is borderline for a squeeze, most players will call but squeeze TT it feels like today. Note that there's 25% more overcards that can come on the flop compared to TT, this means that it just doesn't play well enough in that situation.

I think I want to raise the flop, and that's because we have so many opponents in the pot that there are more draws to be hit. And I like to get value from those. But I also don't think a call is bad. Nice hand.

Also 99 pre, just the call is fine, don;t need to start squeezing this.

I wouldn't squeeze 99 for the reasons already mentioned above. I would, however raise the flop multiway nearly always, at least one will like their hand and get sticky.
Thing is, if we flat the flop here it looks great for us to keep the others in but then we a get broadway heart or diamond turn and ppl have multi draw hands and .. well it all just gets a bit dirty by the river too often imo.

I think raise flop and shout 'For SPAARRRTTAAA!' if you get raised and ship it.