Hi and welcome!
I've only been at saltwater about 8 months, have a 60 gallon tank, but will help out with what I can.
In terms of filtration, if you're not doing a sump, I'd just go with a skimmer and not even worry about a HOB filter. I don't have any experience with sump as I don't have one. They are a nice addition though not necessary, at least not on a tank of that size.
In terms of HOB skimmers I really like my Reef Octopus.
That lighting would be fine for fish. What lighting you upgrade to, if you decided to, will depend on whether or not you want to keep corals. If you don't know yet or plan to wait a while then you can always upgrade lighting later on. The fish won't care about the lighting.
In terms of lighting I'm in the process of switching from T5HOs to LED, waiting to get what I need to hang my lights, but so far I'm already preferring the LEDs just from what I've seen.
You'll need powerheads (circulation pumps) for water movement in the tank. They provide current needed to keep uneaten food and other debris suspended in the water column until its picked up by a form of filtration (like a skimmer). Its important to avoid any dead spots in the tank so that there is no build up, leading to issues down the road. Corals need the flow powerheads offer as well, some corals need more/less than others so again that would depend. For my 60 galllon I have two of the Koralia 1050s, that may help give you an idea.
If it were me, I'd skip the live sand and just use dry. Most of the 'live' in the live sand is already dead due it sitting in shelves and in an airtight bag. Will save you money as well to go to dry sand.
There is no ratio, per say (that I've ever came across) regarding how much live rock in relation to dry. You could start out with all dry if you wanted. From my understanding 1-1.5lbs per gallon is recommended for filtration purposes
(more is fine), it also provides places fish to hide/etc and space to place corals. I like
Macrorock for dry rock. I started out with 50lbs live and 25lbs dry, I also added another 10lbs live after I cured it.
Also, in case you don't know, you really need to use RO/DI water for a saltwater tank, not tap. You can get RO/DI from LFSs, out of machines like at Walmart, or you can get your own RO/DI filter. I recommend the latter. I have my own unit.