I've been doing a 25mile round trip for the last 2 years. I converted an existing push bike, which was a lot cheaper than buying an e-bike.
I carry a GAADI type spare tube, which you can fit without taking the wheel out, though I try to patch the old tube first.
Get a cape. You won't regret it when it rains.
I use studded tyres (Schwalbe Snow Stud) between November and March (I'm paranoid about ice), but you may prefer to avoid the extra drag / noise. Schwalbe Marathons the rest of the year. I think the Marathon+ is overkill and have only had 4 punctures in two years, but if your routes are prone to glass (mine just have thorns and flints) they might not be.
Good lights are essential. Ideally ones which are powered from the bike battery, so its worth considering that in your choice of bike.
Charging at both ends of the commute is good if you can, but do get enough range to do both ways. There will be a day when you forget to plug the charger in... Also remember that battery range in the middle of winter, with lights, heavy clothes, maybe studded tyres, cold battery etc, will be a fair bit less than the stated range, which is for ideal conditions. Range won't be the same in two years time as it is now, either.