One advantage is that the residential zoning offers cheaper loan options than commercial.

All LLCs have partners.What are my best options to contribute to retirement and maximize tax advantage, either near or long term.

As far as financing goes, there are conventional loans specifically for first time homebuyers that you can utilize to put 5% down (giving you the advantages of the conventional loan with the desirable low money down aspect of the FHA).

I would only seek out this option as a means of a competitive advantage in my high cost of living area to get started.

LLC structures do not provide any further tax advantages and, based on my CPA's opinion, are not as rock solid as some make it appear.

If you have the money to get into your new house I recommend keeping this one as a rental there are to many benefits not to take advantage of.GOOD LUCK IN YOUR DECISION 

You are eligible for a traditional mortgage (these offer the most advantageous rates and terms as they are backed by investors) as long as you meet the requirements below:-You have a Social Security Number (SSN) or Individual Taxpayer Identification Number (ITIN); and-You have current, verified status, which may be documented by a valid employment authorization document (EAD), or other documentation showing immigration status is current (e.g., Green Card, work visa, etc.).If you do not meet those requirements, then you will have to find someone who offers private loans.

I would keep buying 2-4 units until you max out your DTI and then switch to looking at larger units as well (take advantage of the low interest loans while you can and build a track record for commercial lenders). 

There are several advantages to SFRs.   

This is a great place to learn and to meet people so take advantage of all the great resources.Read Beginner’s Guide to help you get started: http://www.biggerpockets.com/real-estate-investingLots of luck.