Residente Permanente

I was planning on walking from the San Ysidro bus no. 907 stop about 20 minutes, or 1 mile, to the border crossing. I thought it was a short walk to the airport after that, but it sounds like I need to take another Tijuana bus after that? Also, I thought that the “visa” cost was included in my Aeromexico plane fare that I already paid, and all I need to do is fill out a short form on the plane...