Just looking for some pointers or advice

So I set up a saltwater tank for my first time a week ago, with little to no experience or knowledge with salt.. it was a gift for my daughter and the guy at the LFS told me to give it at least a week to cycle the tank and then bring in a water sample, so today I brought in the water sample, and everything checked out. PH was 8.2 and 0 nitrites and 0 nitrates. Salinity is 1.0024. So I went ahead and got a diamond goby and a pair of perc clowns and couldn’t resist the chocolate chip star. However after doing some reading on the forum I am a little concerned with star. Basically the first thing he did after releasing him into the tank was crawl to the glass and up to the top corner of the tank where the power head flows as if he’s skimming the water, and he has a couple legs out on the water line but no tentacles out.. he’s definitely in the location with highest current in the tank. And also my bigger clown is swimming vertically a bit, but so far hasn’t seemed concerning, the clowns don’t seems stressed whatsoever, I fed them all some blood worms and since the star was at the water line I dropped some on one of his legs which he quickly devoured. The sleeper goby instantly went to work making a refuge under the rock in the tank. He hasn’t been out since.. I am running a 29 gallon tank with a marineland penguin 200 biowheel power filter, and a marineland 100w heater. No skimmer or anything else. I did add a digital thermometer and thank god because my water temp was at 81f. My spouse keeps the house at about 77 during the winter which is usually too damn warm for me, so I set my heater at 75 and it still is coming on every once in a while even when the thermometer reads 78... I’m trying to hit that sweet spot of 77.. any suggestions? I feel pretty confident about the tank, the guy at the store told me the star would be the first one show signs if anything in the tank is wrong, and with the vertical swimming of the clown, I just want some reassurance or any suggestions.. also looking into the idea of a sump.. any suggestions in relation to that as well would be greatly appreciated.. I haven’t yet bought a light for the tank, I have a freshwater tank next to it with a light so for now I figured they’d be ok, until I decide to get some anemones or corals.. any suggestions for a cheap light ( I mean nothing more then $50) that would do well for corals? I did read something about stars not being reed compatible.. I would’ve hoped the guy at the store would’ve said something to me before I bought the star. But I’m kinda in love with the star, and still pretty set on doing a reef tank. All the advice is greatly appreciated!