My family consists of my wife and three kids, and I’m currently the sole earner.

For the LTR outside CA, forming an LLC in the state where the property is located can reduce administrative costs and avoid double franchise taxes in California.

@Will Almand A cost segregation (cost seg) study can accelerate depreciation on your properties, reducing taxable income by reclassifying components (e.g., appliances, HVAC) into shorter-lived categories.

The BEST method for real estate investing is very simple: increase earnings, reduce expenditures, save, and invest from your own funds.You should focus on increasing earnings and learning how to manage your budget.

The penalty can be reduced, but there's a fee (or you take a higher interest rate). 

There are alternative programs out there with reduced cost, but you are typically looking at 20% down. 

To answer the first big question in your post — single family vs multi-family — I am firmly in the multi-family camp.

Repairs made while the property is your primary residence are not deductible, but improvements can increase your cost basis, reducing future capital gains tax when you sell.

Quote from @Devin James: In one of our development projects, the City staff asked us to remove 40 units from our concept plan.This wasn’t requested by the City Commission at a formal hearing, it was the opinion of the staff.Our original concept already proposed fewer units than the current zoning would have allowed.Here’s what erasing 40 units means:- 40 fewer homes for buyers- Over $1M in lost profit for our team- Fewer tax dollars and impact fees that could’ve benefited the City’s infrastructure & servicesWe gotta get betterEveryone wants more affordable housing, but not everyone wants to do what it takes to achieve it we never listen to the recommending bodies. we move for city approvals and work closely. the other thing we do is keep going back to the same groups over and over and over and over every month on the same agenda and make very small reductions like 2% or 4% and that reduces and beats them down eventually they accept what you want. it's just before beating a dead horse. we keep tabling until they give us something we all agree on then we go to vote. in our city in columbus we have to get recommendations but that's our strategy. we used to come out as aggressive as possible. we typically study developments in the area and keep it very similar in terms of density. we have a track record of very controversial projects and litigation and not taking no as an answer. after a year of that haha I can tell you it's not worth it. now we are more relationship based and buying the right kinds of plots of land. if the numbers don't work on the front end don't do the development. 

This type of deal can also help you minimize upfront costs, as you’re reducing the cash needed to buy the property outright by aligning the seller’s financial outcome with yours.While there may be details to work through, such as crafting a solid contract or ensuring alignment with any financing you bring in, these can be easily addressed with the right team in place.