Consider tandem or a second floor for storage.. Also consider the snow and the garage access. I think a 3' door and a "double door" for the automobile would be good.. Also consider the activities, such as washing the car, maybe a car port is better, or a combo port and garage... For some reason, ever since the days of the Model T , garages have been poorly designed, generally too small.. The automobile is not a prisoner, to be confined in the smallest possible cell... Automobiles are ever becoming larger as are our possessions. If no-one ever sees it, why even have a door ??

Also I would not be bothered with centering the front door. Show a full elevation picture because it was obviously offset for a reason. Symmetry often times is overrated.

Yes but what size is your overall unit? A double front door really needs to be a 6' wide opening as you should have the main leaf be 36" minimum. Now the opening could be made larger potentially but then you will end up needing to reframe the door opening which may or may not be possible with the limited info you have offered.

I like the ideas! Keeping the plumbing in the same place is always the least expensive way to go, but no matter what, it's going to be a $30K remodel if you are buying a tub and creating a new shower, vanity, etc. So putting in a pocket door will not add that much if you're going that route. I have a situation now where I have a linen closet door and bathroom door opening as your drawing. They are always banging into each other and the doorknobs get tangled up together because I leave the linen closet door ajar because the cat likes to sleep in there. I'm changing it to a pocket door and linen cabinets. The foot print is smaller for a tall cabinet and for me, a lot more functional although Kitty will have to find a new place to sleep. I'm actually using a tall kitchen pantry cabinet as it already has roll out shelves. But it does add to the cost, $4K. The closet is just framing, drywall, shelves and a door. Probably less expensive than $K. Take your time, find someone who knows the building code and keep playing with your plan.