I just buy whatever they have a HL. They don't last forever, but I do have mine on probably 60 hours a week. I think the heating element must give out. My wood burners last me about 6 months.
I use a glass cutting mat. It's nice because it is marked 12 inches by 12 inches. That way I can make precise measurements. I use the HL one that is in the scrapbooking aisle.
Don't pay extra for other blade tips. Trust me, I don't think you'll ever use them.