yes, anecdotally I think that is true, although I did my first report online (but that was over 2 years ago). I would still try it as there's nothing to lose if you do it online 14 days before the due date. If it gets rejected there is plenty of time to go in person.
excellent. If you have friends there, just ask them to help you, you then don't need an agent. If you have a visa opening a bank account is simple and then 2 months layer extending your stay for 12 months is also simple. You can ask here for more advice nearer the time. Good luck.
Once you get out of Bangkok it is quite an easy drive if you are a competent driver, it is dual carriageway all the way. Watch out for the orange (roadworks) signs as they often give very little notice of roadworks.
It is a long drive to do in one day, I have done it a few times from Hua Hin, but that is 3 hours less than Bangkok.
The statistics are high for road deaths here, but I suspect that is because of the number of deaths at night time on scooters when under the influence of alcohol (Thai and Foreigners), so avoid driving past about 6pm if you can. Good luck.