I'm siding firmly with the OP, both on the garden and on the snow in the driveway.
She has not said she won't shovel the driveway. She has said she will not get up in the middle of the night to do it. (And for many of us, shovelling at 6:30 AM would be akin to asking a morning person to go out and shovel at 1 AM). It does sound totally unnecessary, since the snow is never more than ankle-deep. My little Honda Civic could drive in and out of that easily.
Or perhaps they could reach an agreement whereby he shovels the snow, since it's so important to him, and the OP does some other maintenance job, just as power-washing the fence come spring, or raking leaves in fall (or does that have to be done in the pre-dawn hours as well?)
As for the garden, my attitude would be, "You want a nice, well-trimmed garden complete with flower beds and vegetable patch? Go crazy, good for you for being into gardening. It's all yours." I do think the mowing should be done more often if you are going to have a lawn, and the OP and bf should share in this chore. But the vegetable patch? That seems to be the sister and BIL's project. As long as OP doesn't expect to share in the harvest.
The person who wants a nice garden, should be the one to maintain the nice garden. Personally, I see nothing wrong with the overgrown wildflower look in an urban setting. I know plenty of urban gardeners who have removed their lawns and replaced them with wildflowers and shrubbery that's native to the area. It looks absolutely lovely, and people who walk by stop and admire.