Adopting a used SW tank

[jus68]

I'm a newbie and I'm sooo excited as I'm 2 weeks away from getting a used SW tank.

It has a 75G Display with 25G Sump and a small refugium.

I've spoken with several staff from LFS and I'm getting different opinions regarding how to move the tank and its contents (live rock & water) and now more confuse then ever and would love some feedback on this.

Questions:

Should I keep the preexisting water or make new water? Should I cycle the tank all over again? There are 50lbs of live rock and some live sand, should I keep the live sand? (i've been told it could be contaminated) What are things I should look for before and after moving the tank? Any others tips...

Thanks in advance for your time and comments.
Alex