Hi, I can't advise you on temp specifics for this frog, but if it spends a lot of time at the top of the tank, maybe it's warmer near the top? Closer to the heat lamp if you have one?

Different colors of crickets should be fine. New frogs often are a bit hesitant to move around and it's a good sign yours isn't hiding completely. Frogs aren't very social, but if you decide to get yours a buddy, it should be the same size roughly and the same species. Some different kinds of frogs have different levels of toxicity and sometimes, over time a more toxic frog can poison a lesser one.