I had a pool last year for my son. Below is the filter / pump combo I used with my pool. For chemicals I literally only watched the chlorine level. Even that I just had a chlorine float and left that in the pool.
If it was high I’d take it out and let the chlorine burn off.
Hey there! Pool guy here!
Putting the equipment on top of the tank will be a nightmare. Here's why: the pump you picked, as well as all other cheap pumps, are not "self-priming", so they will not work unless they are at or below water level. Self priming pumps are a few hundred bucks for anything decent (look at a Pentair Super Flow as a good entry level self priming pump). Furthermore, every time you have to service anything, the spilled salt water will be difficult to contain.
A 1/2 Hp pump is way more than plenty. Also, don't get hung up on GPM ratings. Unless you are able to calculate the total dynamic head of your system (tip: you're not, and neither am I), you will not be able to get a true handle on your GPM.
For the DIY tank I built, we used this: Intex Krystal Clear Cartridge Filter Pump for Above Ground Pools, 1000 GPH Pump Flow Rate, 110-120V with GFCI https://www.amazon.com/dp/B005QIYL7E/ref=cm_sw_r_cp_api_RmGNzb87AJTFN
And it worked great.
If you plan on having the tank be up for any significant amount of time, you'll want to install shutoff valves right before the pump and after the filter so the tank doesn't drain when you open the filter to clean it.
Also, a great way to get awesome equipment for cheap is to grab a free jacuzzi / spa. You can always get free spas on CL, because they are a bitch to move. Grab the spa, scrap the shell, and you'll have a nice pump, filter, timer, heater, etc.. just watch out for 220v / 120v if you're not comfortable with the electrical drop.
What else?
EDIT: pumps move the water, and the filter takes it. As long as the pumps flow rate doesn't majorly exceed the filter's capacity, there's no issue. Filters don't "make" GPM, pumps do.
Intex Krystal Clear Cartridge... https://www.amazon.com/dp/B005QIYL7E?ref=ppx_pop_mob_ap_share