I think Neal may be over-thinking this a bit. But the idea of a perf pipe is a good one. Dig down a foot...maybe 16 inches and lay the pipe right down the middle. Use a pipe sock or landscape cloth to prevent clogging. Then lay in the gravel to cover the pipe (about 1 inch below the finished grade). The last inch should be paver sand or concrete dust or something similar. level that and lay in your pavers. As long as you're not laying soil against the wood on either side, the finished grade can be wherever you want it. The only concern is where the perf pipe will end. Do you want it open to the ground in either direction or would you want to continue the trench to a convenient location?
As far as the footers are concerned; if they are visible at the surface, you will have to cut the pavers around them. If they are at least as deep as the depth of the pavers, just add the same sand and lay the pavers flush up against the post (again, you may have to cut pavers to make them fit within the pattern you choose).
One last thought: polymeric sand is great as a finish sand between the pavers, but it sheds water rather than letting it soak in. So you may have more surface runoff than expected. OTOH, regular sand will allow water to seep into the soil and gravel, but given the location between buildings, you may not want that to happen, even though the perf pipe is there. It's above my pay grade to make that decision for you.