Assuming that the conditions above are satisfied, wouldn't it be the best option to search for a deal that is as close as possible to the maximum FHA limit, and the one that has 4 units?

Also they may limit your ability to obtain better rate mortgage as you may only have commercial rates available.

Does anyone know any other lender who do not have such limitation on non owner occupied HELOC loans?

You will be limited on your options but a small lender or HML should have an option and then you can refinance out. 

However if your time is limited or you have absolutely no interest to be active in real estate for whatever reason, then investing via syndications is a great way to invest considering its benefits.

You will also get the best rate and limit the fees you have to pay.

They charged 5k per person to increase one’s credit limits and help them access business credit lines. 

Once you get bigger, and exceed some of the limits of conventional mortgages (4-6-8 properties) then you’ll be in a better position to start looking at commercial loans and make the switch over to an LLC.

The syndicators handle all of the work and the limited partners (you) are just providing money.

What can be built over the Storm Drain easementAny other limitations/factors/etcThe land has been on the market for 55 days and had a pending sale a month ago that fell through.