As a former EMS'r (like several of the others...)...

Kerlix! Or some other lesser-known brand. Yes, it's different than gauze rolls, they're multi-ply and thicker. In a pinch, you could just smack it onto a wound and use it as a base layer for hemorrhage control.

At least one 10x30 inch trauma bandage. Pricey (for what it is) and bulky, but great if you actually have a big injury, or as padding for a splint. Speaking of which, SAM splints are pretty nice, but the wire cage ones are just as good for a first responder and cheaper. Plus there's even odds that EMS will just pull your off and resplint it anyway.

Maix pads are great. I actually tried soaking one once; something like 6-8 oz of water when sopping wet. Make sure you buy the "heavy" flow, not those stinking panty liners. Fat lot of good those will do you, unless you have leakage issues.

Duct tape... not so great for occlusive dressings. It doesn't stick well when wet. The 'plastic' tape from the hospital is great (3M makes it I think). Just take care you're not wrapping it circumfrentially and making a tourniquet.

Ditto the triangles. Don't do the wussy civilian-size. Go big, like 42" or more a side. Try making one "normal" size and see how comfortable your arm is when using it as a sling. they're tiny.

Just for everyone's edification, some of the ER docs at my work did a study on those commercial "blood stopper" products: Celox, plain old gauze, quickclot and something else. Controlled, identical injuries on animal models (sedated). Essentially no difference in blood loss, though some minor differences in re-bleed rates. granted, it was a small study and a lab environment, but think twice before dropping $30 on something that may be lots of hype. I know I don't carry it. I just have hemostats, and know how to use them