Welcome to the forum! I'm happy to see you've got your boy in a nice big tank with lots of room to swim! You might consider adding in a few more plants for cover, or some other decor. Personally, I'd add some sort of a cave for Scuba Steve to hide in when he wants some privacy. I think I see a heater in the back of your tank, but I don't see a thermometer so I'd also recommend one of those as preset heaters are notorious for being off by a few degrees. The glass & suction cup thermometers are the most accurate. If you prefer ease of reading, get a stick on one and a glass (the stick on for a quick glimpse & the glass so that you know that the stick-on one is being accurate).
As for the algae problem, likely the culprit is too much light. You could try turning the light on only when you are home and looking at Steve (evenings, for example). Or move it away from any natural light (ie windows). Other than that and a good scrub of the tank walls, I don't know how else to advise you about the algae.
As per your pH, I'd leave it as is. If you try to control it with chemicals, you'll have more trouble than it's worth and 7.6 is not bad at all for bettas.
Betta's are perfectly happy to swim solo, so the only reason to add anything to the tank would be if you wanted another critter in there. Because you already have 2 snails in there, I'd leave it as is (snails can be pretty messy)