Jessica, if you live in Harrison NJ we can come over and help sometime in the near future.
If you got all that stuff for $100 and you like projects then GREAT find.
I suggest you come up with a project plan and stick to it, stop looking at all of the stuff you purchased and trying to tackle it in one shot, overwhelming.
I suggest, you work on your stand and main tank first. Clean both tank and stand, paint, stain or poly stand if you want to, ensure its still solid or reinforce.
Then deal with the main tank, clean it up, restore it back to usable reliable grade. I did not read everything you have written but once you clean it up, repair the overflow and plumbing fill it up and leave it filled for a few days, lay paper towels to test for water drips.
Once you have your stand and tank in order get to work on the sump. That sump design can be changed to a much more practical design and you may be able to use some of those glass panes if you clean them up poprerly, new blades from home depot are great, do not use dull blades create too much work.
Once you have your sump in order, tank, and stand, connect all the plumbing together, get your return pump in place and if you wish begin clycing your tank by filling it up with water.
While the tank cycles you can then work on cleaning up those lights or depending on condition of those lights just buy new lights. You are new to the hobby of SW tanks therefore you will not be keeping hard to care for livetock such as SPS corals, you can buy a light for that tank for $250 $300 with brand new bulbs and your LPS and softies will be fine but first check if you can clean up those lights.
Try not to fall in the "light dilemma". Your tank will need to be running for many, as long as a year for you to begin adding serious corals. most easy to keep softy corals do fine under standard aquarium lighting so if the lights work fine and the bulbs are old dont worry too much about it, clean it up and use the light. Once you are ready to add corals that do better under fresh T5 bulbs then you can begin replacing the old bulbs.
Fish, starfish, snails, shrimp, sand, live rock, crabs and easy to keep softies DO NOT need fancy lighting, regular lighting is fine.