I currently have a European based property investment company with capital to invest in the us?

Different company?

Code § 7701 - Definitions, my understanding is that the answer is NO, but maybe I am wrong.As the actual rate of withholding is 15% of the sales price, and as the refund (if any) would be "within 90 days", it can be a major setback for my company´s flipping cash-flow because 15% is way higher than the taxable income (and of course than the tax itself), so we would be in the necessity of capital injections to flip the next properties.If any of you have comments on this, it would be very helpful.Thanks in advance

I personally use a service for all my LLCs I use a company called Prime Corporate services and have a holding company with all my LLCS under them.

If you are an agent you can also ask a title company to help you create a list as well. 

Kevin,  I tried working my sign company and lending, it is a lot. 

i.e. what don't I know about managing a property management company that should give me pause about this?

One thing that stands out is the issue of hitting the preferred return on a periodic basis.

Quickbooks allows for you to add multiple debit & credit cards/bank accounts associated with a company.

Have you considered either studying property management or hiring an experienced property management company?