Great to hear maggie.
Depending on what you want to do with the old tank there are a few different ways to go about this process.
If you want to totally take the old tank down and you dont plan on using it for anything anytime soon then you could put the fish in a bucket(s) of some sort. Transfer the substrate via a clean dust pan or pitcher or something like that.
Move your LR
Move your water over. (easiest way to do this is to get a PH and put in th eold tank. Pust some hose on the outlet of the PH and run it to the new tank. Plug PH in and let it pump water from 1 tank to the other.
Then move the fish over.
It sounds like the new tank has its own filter with it. Yes you can take the bioballs out and just the wet/dry as a sump.
If your gonna use the old tanke for something then you could set the new tank up and put freshwater in it and bring the SG
up by adding salt. Let run for a few days at tank temp and correct sg
and then move the substrate and LR
and fish as described above.