The canister will be fine, just clean it out every week by rinsing all media in tank water during the PWC
. i use one on my reef tank, and have no problems with nitrates because I clean it every week and alternate changing out media every week.
I would add all the LR
now for the cycle. As said by Deb, the LR
will seed the base rock and help the cycle go faster. It's better to get everything in at the start of the cycle so that BB can grow on all of it.
Good luck with the tank! And keep us posted on the progress.