Hi Ragnarok, glad you like it
1) There is no set limit, but if your files run wild they will probably get deleted. A few gigs in a month isn't going to matter though.
2) Neither Shup nor Stashbox support multi-upload at this time.
3) I wouldn't be opposed to some linkage, though I'd prefer links to camelcamelcamel or camelbuy over link to Stashbox. PM me if you want to discuss that. Or, stick around long enough and I may put the donations button back on the Stashbox homepage.
Thanks for flying Stashbox!