Then I was told by another lender then no I cannot buy this property with a FHA because FHA guidelines are that I could only purchase a mix used property if it's at single dwelling with a commercial space attached to it that is less than 49% of the residential part other property.

This way you don't get nickle and dimed by the contractor and bleed dry of your working capital before a single shovel has broken ground. 

Hello BP,Hope all your investments are doing fantastic.I’m looking for a bit of financial advice.I currently own 3 single family homes under 3 conventional mortgages each.

We also have an offer in on a single family in Menasha to use as an AirBnB. 

Just to clarify your original post,  is the current property just rented out as a single family residence? 

It's two bedroom, two bath, needs new windows, doors, insulation (particularly the second floor), electric, plumbing, HVAC, kitchen, and the detached garage (single car) rehabbed as well.

To use the VA loan to purchase a single family home would require us to move once again which is costly, not to mention it would be the sixth time in 3 years for out family.

I'd go for a well-maintained single family or two family with much higher rents per unit and much lower headaches.

If the "air conditioner" you referred to in your post is a window unit that would fall out when you turned the house upside down, then it is 5-year personal property; otherwise, 27.5-year propertyLandscaping and ground improvements are 15 year property that would include driveway and sidewalks.For a single family rental, a cost segregation study is most likely more expensive than your tax savings could ever recover through accelerated depreciation. 

So, in a few of the single family houses I have recently purchased for rentals, the basements are fairly humid.