I have a small area of carpeted stair that need to be ripped and installed with hardwood.

We'll also have to replace some ceiling fans, light fixtures, etc. and fix some minor issues such as the toilet, closet doors, and attic access door/stairs.

My question to you all is what is a kind and respectful way of asking him what his plans are regarding his (and his family's) tenancy with me should be get ill enough to not climb up stairs anymore (unit is on the third floor, no elevator).

do you have to replace the deck.. how about stairs down then a concrete patio?

These buildings are generally all walk up, have narrow stair way's making move in and move out very difficult, and just do not attract best tenants.

turned the dining room into her master bedroom as she could no longer get her huge frame up the stairs.Then had the washer & dryer plumbed into her new master bedroom so she didn't have to negotiate the stairs to the basement.But always paid on time including rent increases for 4 good years.I am also convinced she cooked & ate our resident groundhog.

She had been living without the carpet and just walking on cement slab for a while before she moved out according to the neighbors. 

Owner also says "Oh by the way the shower in the down stairs bathroom leaks terribly so we are going to replace that ASAP."

Clawfoot tubs are only hard to get up the stairs :)  Put it in place, LOCK THE FOOT BOLTS TIGHTLY, and call the plumber.  

I would like to replace with new spindles.Would a stair company take off these ugly ones and give mea partial credit and replace with better ones I pick out??