Some people dont even intend to get that many however if you are trying to maximize 10 from each partner/person then you'd try to qualify and hold title separate for your own 10 prperties (10 + 10 = 20 total properties).You can also look at credit aspects as well but typically lenders will use the lowest of the 2 middle scores (3 scores per person but will use the middle score).So the most important aspects are the income to qualify for the loans in the case of full documentation loans.

Student debt usually come with a low interest rate, a rate you should should be able to beat with even a decent investment thereby making it more worthwhile to invest and just pay the minimum on your student loans.Of course, there's also a mental aspect to this.

Additionally, are there micro-markets that may offer less cash flow, but more consistent and dependable tenants, rental payments, etc.?  

Don't forget to familiarize yourself with local laws and regulations; hiring a local attorney can help navigate the legal aspects.

Any go-to design elements that consistently resonate with buyers or renters?

Like all aspects of investing, the most important step is to do your research on the home and tenant.Review their original applications to ensure the current residents meet all qualifications.

Financed an investor who purchased an old, but rehabbed 148 unit holiday Inn which consisted of 2 separate buildings.  

Those landlords had best take some time out to study the law.When a landlord implements standards which are designed to eliminate certain aspects of risk, such as minimum income levels and credit scores, and those standards are equally applied to all applicants it is not discrimination or illegal.

The other aspect is identifying what I call "Ugly Inventory" so that you find homes that can still pass an appraisal and not be "Subject to" so that you can do some TLC with repairs/renovations to borrow off of the ARV.

However, you need to learn about it specially the legal aspect behind it so you comply with the SEC but yes, it is possible you can buy properties without using your money.