PEX is your best bet and should be less expensive to install and last longer.

The landlord wants to have carpet installed in the bedrooms only and plans to put the cheapest grade wood look linoleum in the kitchen, living room and hallway.

My remark about inflation was that monthly installments do not increase nominally so real cost of borrowing diminishes over time and cash flow increases.

I'm wondering how much of a hassle is it to calculate and bill the tenant each month and if there are any other things I should consider before I install one.   

@Kevin Co - If you have a windows based computer, you most likely have Microsoft OneNote installed on it. 

I have no problem paying fees since it saves me time (and time is $), but I appreciated this carve out.Shortly after painting we had the new carpet and pad installed (813 sq ft).

Fridges, stoves, etc have free next day delivery and installation from Lowes and Home Depot.

New doors, figure $5000, exterior and interior, install, HW, etc..Design Changes: if you mean structural work, it could be $2000 it could be $10,000.Turn extension into garage: I would have to see the ins and outs, but maybe $5000 assuming there is a suitable slab below it, and no driveway work needed.How does the MEP look?

Install heat tape.

However less than a month later the tenant is asking me if he can hire a electrician to install a new additional 220 outlet so that he can install a coffee bean roaster (he wants to open up his own coffee shop in a few years and is trying to build up some capital by selling his own roasted beans).