If someone else books and pays for a hotel for me, but it is reserved in my name, can they ask the hotel for information such as whether I had any guests stay over? This is not a business trip; my father booked it and paid for it but reserved it under my name. I'll have a friend stay over and I don't want my father to know, although he did book the room for two people. Can he ask, and will the hotel, tell him who stayed in the room?
He can certainly ask, in the sense that anybody can ask a hotel anything, but whether the hotel will answer or not depends on their policies and their knowledge. If the hotel is reasonably large, they may have no particular memory or record whether you had another guest in the room if a standard room is for 1-2 people. Many hotels pride themselves on their privacy and discretion, but if he's paying, he's ultimately their customer, and it's always at least possible a desk clerk could let something slip or that some aspect of your stay could give it away (e.g. if he calls to inquire about the bill and learns there were two breakfasts or something gets left behind and he gets a call about returning an article of clothing you don't own).
But if you think your father would go to the unusual length of actually calling up the hotel to ask whether you were alone, that suggests a broader issue of trust (which may be more on topic at Interpersonal Skills.se). Even if the hotel cannot or will not answer the question, there's always the possibility he does something like show up in person to check. There's no assurance he can't find out about it, if he is that determined to know.
Can he ask,
Yes, of course he can ask
and will the hotel, tell him who stayed in the room?
They might, they might not. Most hotels take the privacy of their guests fairly seriously and in general will give out little or no information about their guests. However, they are more inclined to collaborate with the person who pays the bill and even more so if the person has status with the hotel chain.
I found that simple questions like "which room is my friend John Smith in" got replies anywhere from "314" to "that's none of your business". It really depends on the hotel and on the person answering the phone.