I'll concentrate on Q 2: At my previous residence in Sydney I had an archway and planted 2 New Dawn roses to cover it and to weave through the vines 2 Jackmanii hybrid clematis, both Danial Deronda. I bought a book on growing clematis before I ventured and followed the planting and feeding guide: I planted them deep in the holes, about 18 inchs from the rose hole, and beneath each hole I placed a goodly dollop of blood and bone along with a about 10 percent sulphate of potash separated from the plants by a layer of soil. I Kept them watered, nursed them along and after about 3 month both plants got hit with the 'Wilt', clematis wilt! The plants collapsed overnight - you need to check the clematis each morning for collapse and as soon as you see it cut the plant off at ground level as close as you can to just above the lowest growing node. I had one clematis for each rose. I managed to save one and from then on the wilt never affected it again, seems it was immune, even a suckering offshoot which I gave to a friend was immune. Eventually mine grew nicely as long as I fed it regularly, kept its roots cool (I placed a few bricks over the root zone) and ensured it was well watered and it produced these magnificent big bluey-purple flowers. Unfortunately my book on the subject seems to have vanished. The New Dawns put on a beautiful show every spring and had a delicious perfume. I planted the roses one each side of the arch and after one season they had covered it over. Pruning, though, proved a bit difficult and now I'm concentrating on roses for a similar purpose that I don't have to prune - I'm putting in crepusule and I already have in Iceberg climbing to grow up a lattice and the red, Dublin Bay. These three roses will flower from spring into autumn, are not overly thorny, have a nice background green for their foliage are to some degree disease resistant, and mostly have a lovely fragrance, except for maybe iceberg. And pruning should be minimum.

Judith, I would not plant a rambler with your modern rose as your pergola is too small. Pierre de Ronsard x two is more than adequately to cover a small pergola - perhaps even too big. Mine flowers in great flushes through the warmer months and has lovely foliage cover too. A clematis would be a much better companion (can give you little advice on this as I have killed seven (one alive, as I finally found a good possie for it).
If you want something more delicate you could you consider a climbing minature like Softee, China Doll climbing or climbing Pinkie. All are excellent performers.
I have not heard of any 'containable' ramblers and recently had to pull out four "Super Fairy" ramblers that got completely out of control.
Cheers Deryn

Judith while the weather is still gorgeous I'd jump in the car and go to Werribee to the State Rose Garden at Werribee Park in K Road.
spend a few hours there and you will see what goes with what and how close the pole climbers are planted. It's an absolute education to see how well they grow with their feet intertwined round the posts.. and so beautiful in the blends they have chosen.. I saw an Angel Face entwined with a Blue Moon and near fell down it was so gorgeous..
Do yourself a treat and head for the park - you will go back in spring I guarantee.

Judith, I fear the 5-6 hours of afternoon sun will be too hot for a delicate little clematis. The archway will heat up and burn it to a crisp. Better to plant a clematis where it will receive the morning sun and no wind and save the archway for the sun loving roses.
Pierre de Ronsard is a rose which changes colour throughout the season. It can be a pale, washed out greenish white in cold weather here in the mountains (it may not get so cold where you are), changing to a creamy pink and then all over pink as the days warm up. So I would suggest something in dark pink to crimson as a contrast which would be in keeping with your overall colour scheme. May I suggest the climbing Chinas, Gruss an Teplitz or Sophies Perpetual. Both flower for a long time, are frangrant and will not swamp the archway. The blooms of Gruss an Teplitz hang down (like Pierre) and Sophies Perpetual has few thorns, so they both have something to offer.
You mention that you plan to grow DA's Othello. I've grown this rose for 5 years, and whilst it's not exactly a flower factory, it is the most beautiful of all the DA's I've grown in the past 20 years.
Welcome to the wonderful world of gardening.