You got nearly the cheapest specs in it's class. It's a new, meme build with no track record. Should be good enough to start with, as long as you don't run out of gears. Probably a solid commuter.
Nothing on that is worth upgrading. If things fail, cobble together cheap replacements and use it as a beater. >>1577109
For base shitheap hybrid, you might as well go with the fx1, in your specific case, disc brakes keep your braking surfaces out of snow, water, and slush, so the fx2 is probably the better choice. Consider making or buying cheap plastic fenders.
Simply gently rinsing off salt water, and wiping off excess water in general near the sensitive areas of the drivetrain, hubs, bottom bracket will make a huge difference. You can use WD 40 to displace water, but be careful to not wash the grease out of your hubs and bottom bracket. Proper lubrication for your conditions also makes a big difference.
Pay attention to tire choice. If you have serious snow, spike tires, and possibly a second winter wheelset might be a good idea. As a blanket rule, you probably want to go wide.>>1577158
RD's are cheap, and frequently available off of crashed bikes. As anon notes, calculate your capacity.>>1577070
The mamacharis, beach cruisers and dutch bikes in 26 have them . Not that common, but still out there.>>1576753
I would check tension, and true if needed, because it will only get worse under your fat ass. I don't think it's emergency stop riding this second, but I certainly wouldn't be going on a tour with that wheel.