Good to know about the random groups...that would keep things handy. As to the bonus dungeon notion, while this did strike me in part due to your nods to ADOM and my own ongoing fascination with Crawl: Stone Soup, I reckon there' s a middle ground of sorts where you could administer the flair but not to a degree of becoming a full fledged Roguelike.
You've already got a carefully, by all indications thus far, crafted campaign...so why not a bonus dungeon/gauntlet made of up the hardest/most varied aspects of the craft in the game thus far----something of a Gestalt dealie? The flair could come in little nods to Roguelikes that would make sense in whatever "special" circumstance would have this place/temporal rift/whatever.
I guess the core of my suggestion was to give thought to something to keep people on their toes and curious again after they beat through the main campaign with a given party.
With paypal, eh, I just don't feel like the hassle of dealing with a middleman, friends have had issues with them in the past, and so on. Just using a credit card online to do simple shopping without any other "entity" to bear in mind besides myself and the bank is pretty well my routine and one I suspect I can't be the only one to have. Established DDL services like Manifesto Games and such would be good for presentation, reaching out to potential customers, professional air within indieness, and so on. My experience with buying Kamyran's Eye 2 from Manifesto Games from a small company went swimmingly for instance.
-One other question: As to post release: How does the future of the game look to you? As in...content patches eventually, expansion packs, sequels---how does all that factor into where you'll endeavor to take the game dependent on sales, feedback, etc?