In my expereince i had to have an episiotomy so can't give advice on tearing but upright was definately the best position when they got me to lay on my back for the episi the pain intensified.
I left for hospital when my contractions were 5 min apart but we had a 30 minute drive i would have left it longer if we were closer as i was happier in my own environment.
I packed three bags! One for baby with all the clothes etc. one for my stay in hospital lots of old undies, maternity pads, pyjamas toiletries etc. and another bag for labour that had my ipod, magazines and food and drink for hubby and me (magazines were not even opened lol) camera lip balm and hair ties.
The best advice i can give you is get as mch information on the birth as possible, dont just focus on the pain it will cause, look at all options, natural assisted emergency caeser etc. because any may happen to you and you will feel more in control if you have some knowledge about it. Also try not to listen to other peoples "horror stories" each person is different so are their bodies.
Good luck and good on you for starting to prepare yourself for the amazing journey of birth xxx