Hi Isantop,
I to is quite new to the kilted life. I’m not kilted all the time but do it as often as I can. I am way past the teen years so I can't help you on the teenage part of society. My experience in general is that people react very positive, everyone wants to talk to you and ask questions.
Stillwater Kilts is a good choice for a low budget and it goes to any occasion. You don’t need to be of any particular heritage for picking “the right kilt”. Just select the kilt and tartan you like.
You should absolutely get a sporran to your kilt. It’s an important part of the kilt. You should also consider two or three hoses for different occasions.