This sounds like a great plan but it might be a little much for your first deal.
Have you thought about starting off with flips and then moving up to projects like this where you are going to have to tear down walls, etc?
The flips will be much simpler and you will not have to deal with the city and getting a variance, etc.
I don't think that you could move out of an FHA financed property that quickly. Also when converting SFR to MFR be very aware of zoning, if the property is not zoned for multifamily properties it may very well be illegal to convert SFRs.
If you intend to do conversions you need to first confirm with your local building inspector that it is permitted. If so you can purchase a property, file a building permit application and then hope it will actually receive approval.
Complicated process that must be done in small steps.
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