New Tank - Questions

Ok so I want to move all of the livestock from an established (2 yrs+) 55G tank to my new 34G Red Sea tank. I will be moving all of the live rock as well.

Question: Do I need to wait for the new tank to cycle or should it be fine if I move everything over? Should I keep some of the water from the old tank and if so, how much? Like 50/50 with new saltwater? I would assume the majority of the good denitrifying bacteria would move over with the rock, and eliminate, or at least lessen the time needed to get the new tank going. Any advice on this subject would be greatly appreciated.

you don't need to cycle if you're using all the same rock, but I wouldn't transfer over any sand, sand gets nasty!

And I dunno about the water-when I upgraded, I used some old water, but not much

I would use some water from your 55. I've done that with each tank move I've been involved with and it seems to help. If you add new sand to the 34g, you will likely end up with a small cycle. Ditto to what Swan said tho, don't add the old sand from the existing tank.