Ed - good to hear from you! At least not everyone is off eating the Thanksgiving turkey.
1 - I have been living out of SA for nearly 12 years, although I return every year. I mention this just to caveat the fact that I am not 100% up to speed with all recent developments.
SA never had a 1926 Mackenzie visit, although it did benefit (my knowledge is skimpy) from Hodgkin doing some courses there. Accordingly, I don't think it has the same critical mass of classic courses as the Melbourne sandbelt. And nor has it benefited in recent years from the infusion of modern talent that, say, Australia has enjoyed. Player and Nicklaus are the only architects of international repute that have built courses in recent years, as far as I can tell. You can draw your own conclusions from that.
Some of the better older courses would include Durban Country Club, Humewood in Port Elizabeth, East London, George, Royal Johannesburg, River Club, Houghton and Glendower in Johannesburg.
You could add to that list some more modern courses - Sun City, Leopard Creek, Fancourt, Arabella (near Cape Town), Wild Coast Sun - to mention a few.
These are the courses you would build a trip around.
2) I will be better placed to answer this question on January when I return from three weeks in Australia and NZ! I will copy you my itinerary when I have it. So I will leave Oz out of it, and also Wales - have not played enough there (maybe Sean or Mark will chip in).
My ranking would be actually as you have listed them:
US
England
Scotland
Ireland
RSA
Briefly, the US appears to have the most variety - lots of classic courses on the East coast, West coast jewels, from Bandon going south; fantastic looking new courses in the mid-West; mountain golf; desert golf etc.
I think England also scores on variety - lots of great links courses and all the fine heathland courses near London, just for starters.
Scotland has many links jewels, but I put it behind England because it has less variety. I put Ireland behind Scotland on purely subjective grounds - but I would rather play Dornoch, Old Course and Muirfield than Ballybunion, RCD and Portrush - but I am not sure there is much in it, and Ireland certainly has lots of cracking second division links courses, as does Scotland. Scotland has less of the new money courses that have hit Ireland over the last decade, for which I give thanks.
RSA - not the same amount of quality courses as these countries. But I would say about South Africa - and it is a big But - that it is probably a superior holiday destination to almost all of the other places, if golf is not your overriding priority. It is a beautiful country with huge variety. Very few people are immune to the charms of Cape Town, the nearby Winelands, the Garden route, the Drakensberg mountains, the bushveld in the East.
3) No plans, but high hopes! I think a trip is overdue. Any recommendations about what to hook it to?
4)Ryder/Buda cup planning in good shape - the dates are nailed down (Oct 2-4), the booking secured at Hoylake and confirmation from Wallasey a formality I believe. I very much hope you can make it, and that we can add a few other nice rounds to your trip.