I'm not sure about the song bonuses to saves. As far as I know they are bonuses to specific saving throws and as such would count toward the +25 cap for fort/ref/will. But last time I checked it was pretty hard getting more than +20 so it won't really matter.
You'll easily hit the +20 general cap to saves as you only have to have 4 items of gear with a +5 to all saves equipped to achieve this and even through using 2 weapons you'll eliminate one possible save boosting slot (shield/torch) you'll still have plenty left. Have fun with your character although if you want to be CS'ing things with impunity a Zen ranger would be more effective.