A note is a unilateral contract under the law, such contracts cannot be assigned without specific consent of the party receiving the benefit or the note holder in this case.

I think the biggest thing that other miss, maybe including @Bill Gulley and probably including my good buddy @Aaron Mazzrillo Is planning for Life Events occuring to the note holder later and transactioneering terms that provide opportunities to renegotiate certain aspects of the debt later. 

Many of the properties on the MLS go very quickly and for above the asking price, making it hard to make a profit for flippers or even holders. 

My only concern is if I'll be able to participate as I am a F1 visa holder. 

That's the backroom operations that holders of SDIRA doesn't see, trustee management requirements. 

I got the person to file a Quit Claim deed to the 1st mortgage holder.

Also, the sooner you know what those liens are and their amounts, the sooner you can negotiate with the lien holder and determine what your over-all "all-in" acquisition cost will be.

At some point, the current note holder will foreclose.  

If those certificates have not been redeemed (paid off) you owe that money to the certificate holders. 

Few more questions Would the property tax liens be taken care by the primary lien holder ?