Just need some advice

So I'm a senior in high school and starting to figure things out in terms of my sexuality. I have come out as gay to some close (girl) friends and my immediate family. I am much happier now identifying that I am gay and not having to hide anything! As part of my new year resolution to be happier, I think I am ready to tell more of my friends (who are guys). I only have 2 concerns: 1) I am so scared to tell my guy friends in fear of what they will think but I don't want to have to wait any longer to tell them. The past times I've had to come out to someone not in my family it went well but I am still scared. I also don't want college to have to be the first time I go through coming out to people. Any advice? Also, 2) My dad has asked me multiple times before if I am sure I am gay (I think this is due to me being more masculine than he is used to). I know this sounds stupid and somewhat wrong but him constantly questioning me has led to me start to question myself (because truly, I have never done anything with guys or girls). Advice would be MUCH appreciated on either of these questions or any other life advice you may have for someone going through this type of transitional phase (coming out & moving away to college). Thank you so much in advance!!