I'll try to answer your questions the best I can!
Well, you don't have to date if you don't want to. Don't feel pressured to date if you don't want to do that. Some people are insecure about certain things, like I'm insecure about sex. I don't however feel like I need to address my insecurity.
Hmmm... I don't have any good advice for this one. I can see how that would be annoying. If it really bothers you, you could politely tell your friends when they come for advice that you don't really want to give advice, don't feel the need to, don't like talking about it, or whatever the reason may be. Hopefully, by doing this, it will stop.
It's not cool to pressure you or anyone into marriage. I'm sorry that your mom has started doing this. Does she know you're not interested? If she already knows, then you'll have to try to ignore the pressure. Also, you should never feel guilty for being aro or ace. I understand that when there's pressure, you often feel guilty, but if you can, try to avoid feeling negative about it. I also understand that this is not always possible, and sometimes we just have to live with it.
Well, I'm not sure if I experience romantic attraction or not, but I do often feel like I'm going to end up being lonely. I try to think about a future where I have a partner of some sort though, whether that be a cuddle buddy, a qpp, or a romantic partner, but I know that isn't the case for a lot of aros. Also, since I'm a rather cuddly person, but don't really cuddle people, I'm considering getting a body pillow to cuddle with. It would be like a giant stuffed animal for me, so I think it would be great. Another thing is I would like to get a cat. A pet can help someone feel a little less lonely, and I think it works for a lot of people. There's no guarantee that any of these ideas will work for you, but this is just what I do. Also, spending time with friends helps a lot I find. Then again, it might be uncomfortable for friends who show PDA. I hope I've helped at least a little.