A service dog has a task and is covered under the ADA.

You may need to adhere to ADA guidelines.

Third, it will be cost prohibitive bc you would need to upgrade the building to current codes including but not limited to: ADA compliance (think elevator), fire escape front and rear of building, and sprinkler system.You can however, investigate 2 other options.

Allow ample room for ada parking stall with adequate space for a van accessible spot.

Become more familiar with it on the ada's website here.

Working from home will make for a more egalitarian employment landscape as accessibility to positions becomes more widely available--specifically those who were previously unable to make get to their physical place of work, whether due to disability, lack of transport, or any number of reasons will now be able to work remotely (I especially think there will be a revolution for those seeking ADA assistance as the general excuse given by employers/HR departments is "this is not a job that can be performed remotely"--good luck getting that excuse to fly post Covid). 

A standard bar top usually isn't ADA compliant.The simple concept of telling others what you do, or are doing, should be a cornerstone of any business model.

@Michael Marchman ADA has nothing to do with residential rentals, this is a very common misconception.

What ADA impact on the property and building4.

Some things you can do is charge a flat rate and cover the difference or call the utility company and get a 12 month average and make that a part of the rents.3: Personally I don't believe in furnishing or supplying anything for my rentals because my market simply doesn't call for it.4: Depending on your area and what the replacement cost for that building is, inflation can effect your policy differently, for this one I would call your provider and ask.5: Common areas much like an HOA would charge, put a common element/area clause in the lease stating the tenant is responsible for a percentage of costs for upkeep of common areas.6: This may depend on state laws, but I would look into if your area requires ADA compliant signage but if you wanted to put a no smoking sign so long as it's stipulated in the lease then it's your call.7: You can't always do much about guests so long as they don't stay indefinitely or cause a danger to other tenants.