I am a frequent visitor but have not posted yet.  

If you are here frequently, it may make sense to have a 2nd residence here.

It is also sometimes a pain in the butt trying to rehab a unit in a high rise since you need to reserve elevators frequently for contractors to use to throw away trash, bring in deliveries, transport supplies, etc. and the doormen get annoyed.

I don't know how much good an LLC does if you comingle funds which (like it or not) can happen quite frequently with investors.

As a mortgage lender, I see this frequently.

I heartily agree with Jessica on the importance of having legal counsel.For closing costs, one tool that I frequently use on the "buy side" is this one from Chicago Title...http://www.rates.fntg.com/?

My ultimate goal is to reach a monthly residual income of 15-30k which would allow me to purchase more property more frequently as well as pay down the current properties quicker.

Also make sure you ask married women for maiden name, check that too.There's a Coast Guard base in Alameda, so this comes up with landlord clients in Oakland/Berkeley/Alameda/etc frequently. 

You'll want to defer to an attorney in your own area, however, I can tell you how it frequently works - the listing contract you have is likely an 'exclusive right to sell' listing agreement, meaning that a particular brokerage, and no other, has the right to sell your property during the term of the listing agreement, in exchange for which they will earn a commission. 

Couple that with the fact that appraisers nowadays make less money to do more work, and the result is frequently a lazy effort because they simply don't care about your loan and whether you qualify.