I don't actually have mine here to weigh, but according to the product description it weighs a total of 7.6 oz, which is 215.456g. 100 fl oz of water is 2.95735L, and each litre of water is 1kg, so you can carry 2.95735kg of water + 215.456g bladder and hoses and such = 3.172806kg or 6.99484lbs total. So the total weight of this bladder fully loaded with water is around 7lbs. Based on my experience running with this thing in my pack, those numbers are accurate.
Directly above the fill hole there is a notch to hang the bag. It hangs in my Granite Gear AC60 just fine. If you click on the photo you can make it out. I'll upload a personal photo with a closer view in a moment.
Hey Bryan. Good question. As the product is sold, no. It cannot be secured to a molle system. However, you can rig up something to secure it to molle webbing. It would be more simple to purchase a molle hydration bladder carrier. I don't know how much they cost, but they shouldn't be too expensive. The stand alone bladders are meant to drop-in to hydration compatible backpacks and carriers. But you can purchase a stand alone carrier that will only hold the bladder and would be compatible with molle webbing. I hope this answers your question.