for more discussion on this topic... I really think that waterproofness is not the most important feature of a pannier.
Ortlieb and Arkel both have great reputations, but are really functionally different - pockets/side load vs. no pockets/top load.
For me, accessibility to contents, a good attachment system and durability are the most important. I like exterior pockets and a side-loader, since I keep my tent & sleeping bag on top of the rear rack - that way I can get into the rear bags w/o unloading the top stuff.
There are lots of ways to keep your stuff dry, the most important thing seems to always be to be ready for rain, do not plan on stopping to fix things up if it starts to rain, when it's too late. I use non-waterproof panniers with dry bags inside (some cheap goretex bags, some trash compactor bags).
There are as many ways to pack as there are tourists - tent & other stuff on top of the rack depends on your carrying capacity. Drying the dew (and rain) off your tent will be different day by day - do you have time to wait or do you need to get on the road? Is is sunny enough to bother to wait? Sometimes you might unpack your wet tent some time during the day to dry it out - only takes a few minutes in the sun, but will never happen in the fog.
Don't sweat it - you will figure all this stuff out in a week or two on tour. Just keep your eyes and mind open.
One of the absolutely coolest things about touring (especially solo) is that *you* both *have* to and *get* to figure out everything yourself. There are no rules - just keep it rubber-side down - don't worry about what anyone else thinks you should be doing, try stuff, make mistakes, learn... and have fun!
As Lance said, it's not about the bike (or the panniers, the tent, the stove).... it's about the experience.
Have a blast...