Ok theres a few things I have for you.
#1 there is no true rule to the amount of rock you need. It all depends on what you want your tank to look like. I have ran my 75g with 50lb's of live rock with a HUGE bioload. The whole 1-2lb per gallon rule is BS and imo
150lbs of rock is WAY to much for a 75g. Infact I wouldnt put more then 75lbs of rock in a 75g.
#2 If you want easy maitnence and the best possible water quality look into doing a bare bottom. For some reason on this forum people arnt in to them but on other forums most people are starting to go that route on their reef tanks because the main goal is to have as little nutrients in your tank as possible and sand beds jsut habbor nutients and release them into your tank. There is no reason to have one other then looks. There will be someone who arrgues with me about this but I assure you there is no need for one. I have 4 reef tanks every one of them is Bare bottom and my corals grow twice as fast as they ever did with a sand bed.
#3 Post your lighting when you find out what it is. If theres one thing in this hobby that new people dont understand its how important lighting is and how many people will tell you Oh that light will be fine but they have no understand of how corals are effected by light.
#4 dont use any live rock, start with all base rock and just use the shrimp to make it live. The amount of live rock you need to quicken the cycle is not worth it. Also people love all the "Critters" that come with live rock but you have no idea how high the odds are that that peice of live rock you put in your tank will have some kind of organisim on it that will cause huge headaches and problems down the line.\
The two best things I ever did in this hobby after having to rebuild my 75g after having hydriods kill 900$ worth of coral because they came in on my single peice of live rock i put in the tank was going bare bottom and using only dry reef saver rock from Bulkreefsupply.