Pretty easy to use, links with my car, investment and personal properties, and umbrella insurance.

Can't fault anyone trying to save a buck but this falls under the "get what you pay for" umbrella. 

Absolutely need to limit your risk here by incorporating or protecting your personal assets in some other way.. umbrella insurance, etc.

But as you prove the system and more importantly the savings, they will bring more properties and other investors under your umbrella.

Is this where an umbrella LLC that manages the LLC's the properties are housed in comes into play?

For a 100+ unit apartment, yes use a LLC, but if you're talking a small portfolio (not many assets to protect) and run your business responsibly (not a slum lord), then putting it in your personal name with an umbrella insurance policy is just fine IMO ... at least until you use up your 10 conventional mortgages (+10 more for your spouse, if applicable); you'll incur more liability driving around in your car than you will on a portfolio like that.

while down the road (once you own a number of properties and have considerable equity) it maybe worthwhile to look at an LLC, a lot of people when just starting out simply purchase a good umbrella policy for additional coverage and protection.  

Question: Can I buy my own property under the umbrella of an Investment Group that I want to start?

The dreaded LLC vs Umbrella policy question.. again..

Do you plan on using an umbrella?