it's very tiny, smaller than a pack of cards and lighter than that too. So size/weight is no problem. I keep it in my pocket and forget it's there very easily.
I DO charge it overnight yes, and I reckon I get 4-6hrs of use from it depending how heavily I use it. Sometimes I'll go out in the morning, come back in the afternoon for a nap or whatever and i'll recharge it for the evening. That works fine for me :) (if you were sneaky I'm sure you'd find somewhere around the place to plug it in for a few mins ;-)
Closest place to disney I dont know tbh but I got mine from best buy. plenty of those around!
All I can say about it is it's as close to perfect for me as I've seen out there. Since it becomes a wifi hotspot, I can connect my phone to it, DW's phone, a laptop etc whatever I need. It's been excellent around Disney reception wise even though the one I have is Tmobile (apparently verizon may be even better but I've been happy enough).
It lets me use my normal iphone with its uk number to receive/send texts if I need to or phone calls in an emergency so no hassle with a us phone and a new number. Although pretty much nowadays I use whatsapp (or imessage) on the phone which uses data and therefore again works over the mifi :)
I've used it for three or four trips now and very pleased :)