2.  Can this type of anti-economy or gift-economy be sustained, developed, and even attain mainstream acceptance?

Well, of course a gift economy can achieve mainstream acceptance. The Potlach cultures of the Pacific Northwest had to have their gift economy actively suppressed (though the adoption of modern money through contact with the colonizing Western culture also played a role). Also, in The Cathedral and the Bazaar the Open Source movement is analysed as a gift economy in which Hackers (not to be confused with Crackers) accord each other status on the basis of how much free, high-quality software they have contributed to the community. People like Linus Torvalds (Linux), Larry Wall (Perl) and Richard Stallman (Emacs) enjoy among the highest status in the community because of the incredibly useful gifts they have bestowed on the community. Google seems to also enjoy high status among the general public particularly because it gifts useful, well-engineered web applications to the community. (On that, see rg's diary is Google Evil?)

However, I think we should be under no illusion that the entire economy can be run as a gift economy. The gifts have to come from somewhere, that is, people still have to work the fields and hunt and forage and herd cattle and mine and craft manufacture the items that then get exchanged as gifts. That is, a gift economy can play an important role in exchange and distribution of a society's product, but not in production. In more primitive societies living in a rich environment where sufficient food can be foraged you can have a gift economy even for the bare essentials. Maybe the voluntary scavenging by affluent people poemless describes indicates at least parts of the US now find themselves living in a situation where one can "forage" for cheap Chinese-made gadgets or even sports shoes, and then gift them to others by leaving them by the dumpster. A gift economy is a sign of relative abundance.

Access to "the means of production" (capital! credit!) as a way to give people choice about their role in the productive economy remains a key issue whether you have a gift economy or a market economy as a mechanism for exchange and distribution.

We have met the enemy, and it is us — Pogo