If they do not pay are we legally able to keep their equipment as collateral? 

I would start here to see that people are coming to the area and not be as worried with why.I'd also confirm what you need to operate legally such as any permit requirements.

Firstly, is this legal/possible to do?

When they start getting legal stuff to fill out exposing all of their dirty laundry, they will freak.

If you need financial help, ask under the "Finance, Tax, and Legal" forum.

Again, this is looking through the Colorado legal lens.

I have never invested in real estate, and if I get Europe, what do you recommend I start studying (legalities, policies, trends) and where can I find the necessary resources/education to prepare to look for deals in Europe?

It would be cheaper for us to list the properties with a realtor and then buy it myself under a different LLC, if I'm legally allowed to do that.

To make sure it's legal, I would dive deep into the zoning/code regulations and try to connect with someone in your area who is doing something similar.

It was a sales contract with, after 9 legal pages of irrelevant information, had a couple sentences added about her commission.I rejected the document, and asked her to provide me with a Property Management Agreement.She then sent me a "Confirmation of Agency Status" one page contract.