I know to watch for when they start limping, but they don't tend to while they're still all-out attacking you, so I end up killing them and getting an insta-fail unless I err on the side of not-dead. :P
And yeah, tricking them into charging into it is how I always do it, but it doesn't help when they've left the area and decided not to return in the next 20 minutes. Do traps disappear after time? I know one of mine vanished when I wasn't in the area, but a Qurupeco (not the target) was, so I'm not sure if he set it off and wasted it or it just timed out.
For the record I'm only having trouble with Royal Ludroth's capture, and it's mostly because I don't have the materials for spare shock traps and pitfalls aren't allowed in most of the areas he likes. Qurupeco was dead easy.
I think I got tainted meat to work all of once in MH1, and not yet in MH3. :/ Of course, I haven't tried that hard.
You can change how you swim? what's it like now? and what is your dodging like? I'm using the same control set-up as you.
The swimming works basically exactly like moving on land, with movement up and down controlled with the otherwise unused second triggers. It gives you a little less control, but also involves less hand contortions.
The dodging...to be honest I changed it right away on the advice of a friend so I don't entirely know what the default is like. I think it has to do with dodging in mid-combo and how it determines which direction you go in. Default uses the point of view of your character and the one I'm using uses the point of view of the screen, or something.