Interesting, I'm not aware of any reason to not use wood in small tanks either. Wood should be quite nice in any tank!
Running a tank at the pH that fate has given you is always a much, much better proposition than attempting to "go against it." Its a lot of work to alter the water and go off to a different place from your given source water and almost always ends in bad things happening some day. There are lots of great things you can do with a very acid tank like that and I think you should be ok.
I do strongly recommend the "rough one inch of mature fish body size (fins don't count) per US gallon guideline" for the first year and a half for all beginners. Its NOT that you can't overfilter and learn to run slightly overstocked tanks, its that its very important as a beginner to have a nice solid beginner experience with what a successful tank should feel like before you move away to something that's different. Yes, there are lots and lots of problems with the inch guideline and they've been discussed in huge threads in this forum, but having the balanced tank experience under your belt once is an important thing!
I also feel that the minimum tank size for a first pair of angelfish is 29 US gallons and the tall version is needed so that they have their minimum 17 inchs or so of tank height. Many feel this is an absolute minimum for the first two angels.
~~waterdrop~~