In my current state of learning everything I can about RE investing, I keep coming across the challenges of getting financing after 4-10 traditional mortgages.

It would be great to also know what areas/service in RE I should steer away from that will be challenging. 

All transactions that your IRA engages in must be "arms length" (no personal involvement).

Engage with others, and magic will happen

What are some of your liability and insurance challenges in your area?

Insurance companies, and this includes umbrella policies, will deny or challenge your claim especially if the damage / claim is high and based on negligence or any fault of your's, READ your small print and don't think you are so good at landlording that accidents won't happen.

You cant have construction drawings unless you have a civil engineering company with you and you cant have a engineering company with you unless you have a property under contract ..So, i would put that property under contract and then start engaging an architect to get a layout/construction drawings and once that is completed .. close on the land .. 

I typically suggest my clients engage a land development specialist to assist with this process. 

The more challenged parts (to the east) are solid cash flow areas that seem to be in the path of progress (new apartment buildings, city-built homes, Penn station redevelopment, etc).

There are probably as many multis in my area that aren't legal as there are legal, but it can add logistical and sometimes expensive challenges.