Now the landlord says i need to cover the cost since i installed it.

@Susan Ali I would start with installing ceiling exhaust fans they wire in fairly simple. 2nd I would remove the water damaged area and see if there is any moisture damage above it indicating a leak from up stairs.

The units have badly installed cheap damaged linoleum floors.

We installed a new kitchen (fixtures, appliances, some plumbing upgrades), new baths (wall/floor tile, vanity, fixtures) and paint/minor carpentry.

Can I add a addendum to a lease to include the electric payment to me rather than Edison on a newly installed solar system?

I plan to install metal roofs, energy efficient appliances, plant small pollinator gardens, and eventually install solar panels (when solar energy becomes more affordable and if my market will allow higher rent for a lower electric bill).My question is if pollinator gardens could be a liability as they attract bees and other stinging insects. 

We put up a wall, new kitchen tile flooring, new closet in one of the bedrooms, painted the 3-bedroom apartment, installed sliding doors in the bathtub, and painted the front and back entrance hallways.

Keeping the same team, but installing a general manager to oversee the operation. 

For example updating the electrical and installing a new hot water tank should only run you $2k-$3k.

Call tile workers and ask how much do they charge per square foot to install wood look tile, and how much to remove old tile.