Thank you for the speedy and informative replies + info guys ^^
On the topic of development speed, given his donations and how active this community still is (as I see, again), why won't he hire staff to assist? Notch of Minecraft got a few people in way later than he should of, why won't Toady? He can afford a single hired hand, surely? Over $30k in the last 4 years, each year. Can't he hire a guy? Yes it's a jump and if he is risk-adverse then he may not want others interfering until he REALLY CAN throw away money.. but $40k+ in each of the last 2 years.
Dwarf Fortress doesn't APPEAR to have the same SALES figures (because nothing Dwarf Fortress has never had a price tag); perhaps open another line of funding in the form of Official Ownership of a Dwarf Fortress copy - charging £5 a piece during alpha is what got Minecraft going - although it's more simple, 1st-person gameplay more easily shows where the money is going. If nothing else, this rant has made me consider donating some more - but good god man, why isn't a rocket up this project's ars* already?
Edit:
Surely if Dwarf Fortress can open another line of funding as in "Buy a licence" then many people, donators and those that are donation-adverse, would purchase. With the one-time-per-person funding, perhaps a capacity for staffing? I imagine that once the Dwarf Fortress ball gets rolling, nothing is standing between us and a retail version.