Dear Last Yazi~
Welcome here where there is no such thing as 'just a kid'. People of all ages have problems, get hurt and have troubles with relationships.
You sound as if you may be more mature than some of those you know, having a high IQ and being in the advanced stream probably means that there is some distance between yourself and some of the others.
You also sound as if you know how a freind should behave - which means you will make a good friend when you meet someone you 'click' with.
True friendship can be rare, and even the normal matters of politeness and consideration have to be leaned as one moves through life. If one of your acquaintances is rude, or another changeable, then they are still very much in the learning phase. That can be very upsetting for someone who is sensitive.
I'm not sure you should actually try to get rid of those you know, have you considered telling them how you feel when they act up? If they disregard how you feel afterwards then might be the time to reconsider your relationships.
As for finding new friends, schools always have fair number of people who feel isolated and not part of a group. Going out of your way to get to know some of these might be good.
Now about talking to others, do you have a parent you might discuss the matter with, not necessarily so they have to do anything, just share how you feel, it can help.
Please come back and talk some more, we are glad you came and are hoping things will improve