Switching over racks and saddles shouldn't be a problem. However if you buy tires make sure your new bike supports the tire size and/or width.

The road conditions you show look normal (I know that's sad). Try to avoid potholes or standing water as much as you can. Basically be as careful as you can. Tires may help avoid pinch flats, rolling resistance, or debris flats, but if you get a new bike, make sure they will work with it.