The bigger your down payment, the lower your monthly principal and interest payments will be.

Fixed rates on 2nd mortgage notes are usually limited to a term loan structure (Principal and interest payments).

For example, what happens if a property can’t be sold before principal payments kick in.

And my first payment will be due on Dec 1.If so my monthly payment would be only for the Interest which is little less than Principal + Interest?

Link to Fannie Mae "Due on Sale" exemptions with transfer to:a limited liability company (LLC), provided that the mortgage loan was purchased or securitized by Fannie Mae on or after June 1, 2016, and the LLC is controlled by the original borrower or the original borrower owns a majority interest in the LLC, and if the transfer results in a permitted change of occupancy type to an investment property, such change does not violate the security instrument (for example, the 12 month occupancy requirement for a principal residence).Here is the link: https://www.fanniemae.com/cont...

Here is a link ( https://www.fanniemae.com/content/guide/servicing/d1/4.1/02.html) to Fannie Mae exemptions to "Due on Sale" clause that includes the following: transfer to a limited liability company (LLC), provided that: -the mortgage loan was purchased or securitized by Fannie Mae on or after June 1, 2016, and -the LLC is controlled by the original borrower or the original borrower owns a majority interest in the LLC, and if the transfer results in a permitted change of occupancy type to an investment property, such change does not violate the security instrument (for example, the 12 month occupancy requirement for a principal residence). 

So is the "mentor" usually the broker (called a principal broker here in Oregon)?

The US is definitely a different market, with a lot of upside for investors (1031 exchange etc, mortgage principal write-off, which we don't have).

Note: Principal paydown on your next investment property can boost that return % if you choose to include it. 

As for the "principal"....I agree with you.