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