What is thickness or mil of this bag? Is bag material water resistant - will water bead up? Is bag durable for basic use? Overall quality?

The material is not real thick, but at this price.... Can't answer the water beading/proof honestly as I sprayed immediately with Scotchgard outdoor water shield, available here on Amazon. That really made it waterproof. I use it as a secondary bag that I keep in my car. If you need to use it on a weekly basis, I would probably give it 6 months life. If like me, it will last years. At 10 bucks, it is well worth the price. This what I have stuffed in it with room to spare. Oh yeah, also have a stethoscope in it too.Bandage Pressure 4" 1Bandage Standard (1"x3") 32Pkt. Alcohol Prep Pads 26Pkt. Antiseptic Towelettes BZK 20Pkt. Burn Cream First Aid 16Pkt. Hydrocortisone 9Pkt. Iodine Prep Pads 39Pkt. Triple Antibiotic Ointment 35Roll Non-Sterile Roller Gauze 3" 2Roll Sterile Stretch (4.5"4 yd) Keflix style 2Sterile Gauze Pads (3"x3") 10Sterile Gauze Sponge (4"x4") 4Sterile Pads Non-Adherent (2"x3") 10Tape Self-Adhere (1"x5 yds) 2Sterile ABD Pad (8"x10") 2

What size is it ? looks bigger then 8 x 1 x 8

The main compartment is 8" (20cm) x 8" (20cm) x 5" (12.5cm). Hope this helps.

I'm looking for something for home use; to keep a few first aid supplies as well as my son's EpiPen. Would this work? I don't want something too big.

It's great for the home/car I keep it in my home on a small shelf when not in use. However, depending on the amount of supplies, you may want to opt for a small first aid box rather than this bag. Check out the pictures I posted with my review to understand the scale and contents. :)