First OB Appointment

what should I expect at my first prenatal appointment? like what kind of tests will they run, will I get an ultrasound?
also, I smoked marijuana 4-5 times everyday before I found out I was pregnant as this pregnancy was unplanned. Will my doctor test for marijuana my first visit? will they at all? what will they do if/when they find it in my system? I haven't done any other drugs, ever. 
I live in Ohio if that helps.