The surface after being sandblasted need to be treated with METAL-READY to etch the surface for the POR-15. POR-15 is UV sensitive and needs to be topcoated unless it's not going to be exposed to direct sunlight.
The adhesive question is kinda hard to answer as you really have no idea of the checmical make up for the adhesive. POR-15 is a moisture cure urithaine and some adhesive may not adhere very well. I'd suggest testing the adhesive on a test panel first.

Good Luck.