Hello! Welcome to the group!
I got my '04 330 back in May. There are noises & vibrations, but I'm chalking it up to being an SUV (I know it's a crossover - but it's still an SUV). I think it depends on what your comfort level is. If you're coming from a perfectly quite & smooth ride, you'll notice the road noise. I had a Cherokee Sport & the RX is much quiter, but I still think it should be even more quiet than what it is.
For the answer to #2, no idea but good questions.
#3 - I've decided that no car will ever have all of the bugs worked out. Yes, they might be more aparent with a 1st generation, but I think everything has it's quirks.
The lag that WWest is talking about does exist. I have found out that I just really don't need to pull out in front of anyone & stomp on the go pedal. If you do, you'll feel the lag and the headlights behind you scream towards you. Gentle acceleration works best on this car (not exactly how I drive in rush hour ).
Good luck!