Hey man, I'll try to answer you.
I learned to drive in 2014 which was before my diagnosis, but I have been hearing voices since 2008 I just didn't get the schizophrenia diagnosis until around 3 years ago.
I've stopped taking medication a few times and ended up in hospital or under the crisis team every time. But I certainly don't plan on being on medication for life. My psychiatrist says I can't stop it but I will prove him wrong. I think I can do it with the right circumstances and support.
I have the same problems you mention with memory and concentration and that has really stopped me doing my best at...well....anything, but especially studying. I dropped out twice before getting my undergrad. Masters took 2 years. And I tried to retrain by doing classes at a local university, but I'm not doing great at that. However, I don't want to work this job forever so I'm trying. I have a lot of trouble with motivation too: motivation to study, motivation to get out of bed and shower.
My functionality is often pretty good now that I have the right medication and a ultra low stress job. However, I still have difficulty often - I forget where sentences are going when I talk to people, or just forget simple words. I get ideas about people wanting to hurt me so I have to talk those kind of things over with my psychologist and we try to work through them. My mind also tends to go down rabbit holes of thinking and I get completely obsessed and lost. My memory is terrible, and my concentration still really bad. I found keeping to a schedule really helps me avoid relapsing - I think that's the most important thing I do day to day, my phone has a lot of alarms set for different things throughout the day.
A diagnosis of schizophrenia isn't the end of the world, buddy. You can still achieve, You just have this hurdle but it can still be conquered.