We are only missing a plumbing license, which I plan to hire part-time soon.

bathroom rehab depends on plumbing but i expect min. 3K for lighter one.kitchen rehab is about 2-3k ; the cabinet is not expensive.that's labour and materials. 

Featuring brand new roof, new windows, completely new electrical system, completely new HVAC system, brand new plumbing inside the house, and all new designer cosmetic updates, luxury inter-locking vinyl floors & luxury stretch ceilings with recessed lighting & full landscaping with new sod up front.

Now she complained the issue of toilet fill valve which caused unreasonable high water bill and claimed it belongs to wear and tear and a plumbing issue.

I don't mind getting no heat/no ac calls, plumbing leaks, section of a fence blows over, etc. 

This may involve hiring licensed contractors and obtaining necessary permits2.Address structural integrity, electrical systems, plumbing, and potential water damage from firefighting efforts.Insurance Considerations: A history of fire damage can affect insurability and may lead to higher insurance premiums.

How are the major potential expenses of the house looking (AC, Roof, Plumbing, Electric)?

A plumbing issue could be causing the problem.

You'll definitely want to make sure the electrical and plumbing haven't been damaged (or know how much they have been).

I had a plumber go over to give me an estimate for converting a half bath to a full bath and he called me back claiming that the plumbing inspector wasn't going to allow him to tie into the type of pipes I have and I was going to have to re-pipe the whole house.