hi, I too would wait till breast feeding is established b4 going onto the bottle. You do get use to getting up at night, it isn't so bad as long as you get some naps in during the day . After saying that i waited too long (5 months) and had a terrible time getting my DD to take the bottle. I used the Medela bottles which i think are BPA free as I had a Medela breast pump and the bottles twisted onto it. This was really convinient as i didn't have to transfer it to another bottle or freezer bag and popped it straight into the freezer or fridge. I would then warm the bottle, put a teat on it and it was ready to go. I would definately consider buying the pump and bottles in the same brand.
I tried to use some ziplock bags, but i thought they were a pain unless you had a surplus of EBM.
There is no need to sterilise if you are exclusively using EBM bc it naturally contains antibiotics to kill off nasty germs.
Hope that helps.