What are the complications, legal ramifications, additional expenses, pros cons, of instead of dumping money straight in, having a partner make the LLC take out the loan.

These are more complicated and the fees are much more than a standard Forward 1031 Exchange transaction, and some Qualified Intermediaries do not administer them. 

They ended up with medical complications causing them to move out in less than a month.  

. :)when (if) i hit 20, the new number will be 30. but i have to tell you, it's getting difficult to attend to them and remember the addresses. having a full time job complicates things a bit.

Yup, but lenders want to put their money in the hands of guys who have a proven track record of success, not guys who are buying their first deal.  100+ units are much more complicated than just being able to do the basic analysis -- the real world issues that you'll face (management, local politics, local economic changes, cash flow forecasting, etc) aren't things you can read about...you have to experience it to understand it.Also, it's very uncommon for lenders to put up more than 80% of the money -- they know that if the deal is good, you should be able to find the other 20%+ pretty easily, which will reduce their exposure.

There are rules, of course, with the solo 401k, but honestly, they don't seem that complicated or restrictive to me (basically, the biggest deal seems to be not buying anything that directly benefits YOU...ie: if you buy a vacation rental, the proceeds go back to the 401k, and YOU can not vacation there...stuff like that).I found the company to create my solo 401k here on BP as well...in case you wanted to do a search, ahem.PS- try not to fret too much about the car(s).  

Any complications if I split the loan by having Friend #1 loan only $70k, and Friend #2 loan the remaining $30k?

The flood zone designations are very complicated and reading through them will make your head spin.

@Jason Carter I do a lot of construction lending, as its complicated and most lenders don't want to mess with it :-)The simplest way to do this is to get the land free and clear.  

I met a whole group of people and it was twice as exhilarating to meet so many people.I also realized I had been over complicating things and that getting started was going to be significantly easier than I had expected from having read too much.While there someone mentioned a strategy I hadn't seen before - Giving multiple offers to the same seller.