Amaryllis

So, my parents are making me quit weekly voice lessons after a month. My voice has already begun to improve (it's fuller, and I can sing louder/longer without straining my voice), but I really wanted to be able to stick with voice lessons because (when I 'm in college) I want to train for opera.

My question is: what kind of exercises can I do by myself to improve breath support. To the best of my (admittedly limited) vocal knowledge, breath support is singing with aid from the diaphragm, which allows one to hit higher notes/sing louder.

I've been singing in choir for five years (I'm in my late teens) and am an alto. I really want to undergo classical training...my voice teacher was extremely talented and could hit the high E two octaves above the E near middle C effortlessly and deafeningly.

Also, how do people sing with vibrato? I can't seem to do it! I can sing pretty loudly the lower notes, but once I get into my head voice it becomes nigh impossible to sing loudly &sound nice!