However  the cabinet boxes come put together at menards and ikea are flat packed (extra work).  

Perhaps updated plumbing, foundation, roofing, insulation, electrical service panel, windows, etc. whereas you may find a 1960 or newer property that has single pane aluminum windows, overloaded electrical service panel, deteriorated roof, galvanized and corroded water lines, etc.

With that said, I have seen some investors approach the deal as a wholesaler would, find a below-market deal or motivated seller to get the property under contract at a discount, and then just get a handyman in to get the property into "liveable condition", touch up paint, make sure everything is functional, do an intense cleaning, and then re-list the property for a small profit after closing costs etc, maybe using a flat rate listing service. 

That should be a flat bonus, that way they are not encouraged to hurry their efforts. 

A "flat" section of the roof was completely redone.

The agent could be transaction broker and do a flat fee of $1,500/$2,000 to get it done.

Pre-constructon contracts are risky if you don't have experience and can be problematic if you have cost overruns or flat out miss the numbers. 

The ones that are the most tenant proof are flat top electric stoves.

If that line is suppling your property than I would assume you would have to have to move the main service panel on to the ADU.

If the tile is flat it is likely that installing the LVT right on top of it will not be a problem @Gayle Melnick.