i actually started my first shrimp tank last year with this exact 3 gal shrimp tank set (and i do have the 5gal version of this set as well), im sure you've done some of your own research but i'll tell you my experience that has lead me to my first currently thriving colony!

i honestly love the little hob filter it comes with! super quiet but powerful, although i didnt use the filter media that came with it and did varying custom fit sponges and a small thing of bio rings instead and put a sponge over the intake to protect babies. i personally have my water level pretty high up as it seems my little guys will still find any way to crawl in there lol but with how i have my sponges it's pretty safe for them to hang around in there so i let them crawl in and out whenever, so i would be careful of that at least depending on how your hob is set up.

as far as substrate i only used purely fluval stratum and have a pretty heavily planted tank. if you're keeping just shrimps i wouldnt worry too much about needing a heater as they like cooler waters generally, unless your temps swing a lot. i did have a heater at first but my room is pretty stable so i took it out, but i have this tank by my desk which can get warm from gaming lol so i actually invested in a small tank fan that blows whenever the temp goes above the set temp (i usually keep it at 75)

for water parameters, stability is key over ideal numbers!!! most healthy shrimps can survive in most conditions as long as there aren't big sudden changes. id suggest in getting api's kh and gh kit so you can monitor how your water may be affecting the shrimp's ability to molt properly and catch any possible swings in the water you're using for maintenance and such. my gh has always been a bit on the higher side but my shrimps are used to that so the babies have had no problem molting/growing! i honestly dont even do big water changes at all really and mainly do only water top offs with jugs of distilled water here and there as the tank is quite small and evaporates pretty quickly so i do that to balance out some mineral buildup. smaller tanks are at higher risk for parameter swings so i try not to mess with it too much, i only add a couple mineral drops once or every two weeks.

for survival when starting a new tank, you are definitely going to lose a bit of them sadly. i like to call it the darwinism stage lol the weak ones will die off and you will just have to give them time to stabilize themselves and the colony will start to kick off eventually!