-Keeping any common areas and the exterior of the building clean as well as cutting the lawn if there is one, here in WI of course, someone has to shovel the sidewalks and stuff whenever we get snow too.

He said in these older neighborhoods, he could test any sidewalk and find lead.

Tenants tend to tear up everything you've done, and it you aren't careful, you will end up doing the work twice.Do all the work on stuff the tenants can't reach: new roof if it is needed (OK, I have had a tenant tear the roof off, but they don't normally damage the roof).Repair sidewalks, do structural work, repair the plumbing, perhaps a new heat source if needed.Get the landscaping under control, but dont improve it.

About halfway down the hill, ground water would come out and make the sidewalk and stairs slippery.

Laughing and dancing in the street and on the sidewalk. 

Well it is not recommended to do but if you want your sidewalks de iced.You can always go get water softner salt.

HGTV never shows anyone shoveling their flip's sidewalk in negative temperatures so the neighbors don't complain to the city.  

Seller told us that in the lease, it states that the tenants have the responsibility to have snow removed from sidewalk by a certain time (I think he said by 7am or something, whatever the local law states).

My mom is literally a few houses down the sidewalk.

In the event of a loss/lawsuit (say, for example your tenant's broke friend "trips" on the sidewalk and suffers emotional trauma that renders them unable to work for life), ALL money sources will be listed - your insurance company, the entity that owns the property, you personally, all other assets (LLC's, businesses, etc.) owned by you personally.