Your FSB to Dram ratio determines the RAM speed. Since you have a ration of 1:2 at FSB of 200, multiply by 2 to get 400mhz. This ram could run at 533mhz, it would require the FSB to change to 266mhz, or the FSB to DRAM ratio change to 1:2.65. If you want to , or can, you can overclock the FSB to 266 to get the memory (and everything else) to run faster. I dont know if it can OC that high or not.
If you add another chip it will run dual channel automatically, no need to do anything.
New ram will run to what the FSB dram ratio computes out to, if it is on automatic, it may have setup problems.
Also dont worry about the timings, they dont really mean that much anymore. The SPD timings are what is programmed into the RAM to tell the computer how fast to run. THey dont always use the SPD timings though, so dont worry.