もいいですか is like asking "is it okay?" and I found when I was studying in college with a Japanese foreign exchange student he recommended I use this phrasing. Keep in mind that in my early high school days I was using 質問がありましか。Which is clearly as rudimentary as it gets. Using 質問してもいいですか。Might have been better for my situation since we were friends and consistenly helped each other study though. I recall hearing ききませんか in the past but I can't comment on it personally, but I have never heard たのみませんか used.