Yes it is possible for you to change your college. It is normally possible if your college and the college to you are moving comes under same university. You can go to another university with same trade provided your college accept the transfer.

Your college will lose all those fees that is expected from you in your 4 year studies. So they may/may not ask for compensation. Again you should have a valid reason to get it approved from university such as change of house, family moving to new place. Please contact your HOD for this matter, he will lead you to the relevant person. It is not normally appreciated, however you try your luck

Yes, you can change college in the same university. Go through the university norms. You will need a certain SGPA in 1st 2 semisters.