If your looking to switch from freshwater to saltwater it's a good thing to take everything out of the tank rinse it down pretty good. After that if you do want to run a sump no need to drill they have box you can hang on the of the glass that does the same exact job. What you have in your sump is up to you usually a protein skimmer and what not. As for what type of water rodi
water is the best you can use. I used tap on my first reef it wasn't bad but you can tell a big difference when you use rodi
water. A lot of people say live rock I don't like to bring live rock into my tank I did on my first reef and I got a lot of clingers on the rocks that I didn't want so I stick with just regular rock and let that mature over time it's cheeper and you know your not bringing anything you don't want in the tank. Live sand is ok to use it gets you cycle going pretty good. I would say 4 20 lbs bags of live sand at least a good deep sand bed is better. There's a start for you play a little with your first reef tank take it slow an let it grow make sure you have adequate lighting at least a 4 build t5 ho
fixture or two of the led
lighting system I can't tell you there name but some one should know on here.