3. any examples people have seens before of similar projects?

No - not without pics.

There are a gazillion garage systems out there. That said, we have a removable ramp (boards) to get our mower up our steps. While it might not be the most convenient, if what you want to do is have a place to lock your snowblower and mower up while not in use, you might not need a structure you can walk in. Consider a lower box. It might slide by the historic district rules and meet your needs. Often, things can pass a historic district if you can prove it is a historic look. If your house is old enough, it probably once had an outhouse/privy and probably not an elegant one.

How big is the space? There's a big difference between a 6 by 6 foot root cellar and a 20 by 60 foot basement. Photos and a floor plan sketch would help.

A good source of referrals would be your neighbors or the HHA.

Maybe a closet designer?

PICTURES how the heck can we answer this with no context .