Hiya, you could probably do with a bit more live rock if you could get it, 11-12k would be better
Using salted RO is fine, I used to use it with my nano, but there are a couple of things you need to be aware of, what is the salinity of the water you are buying? If you want to keep corals, you need it around 1.025, alot of shops keep theirs a bit lower, so I ended up buying salt to increase the salinity. You will also need to keep a bottle of plain unsalted RO for topping up the tank from evaporation.
If you use salted, just pop it in the tank, get it up to temp, then add the rock, transport it in water if you can, it will shorten the cycle, then add the sand & your cycle has started
I test daily, salinity, PH, ammonia, nitrite & nitrate, plus keep a thermometer in the tank to keep an eye on temp. You will notice ammonia first, then nitrite & finaly nitrate, once ammonia & nitrite are Zero & stay zero for a few days, you should do a good size water change (I did 50%) to bring down the nitrates, then watch the stats for a couple more days, if all stable, then you are cycled
I'm far from an expert, there are people on here who have far more experience with marines than me, but this is how its worked for me.
Good luck & have fun!