I'm not sure where you are getting the 25V 100 Ohm values. Resistors are measured in Ohms not Volts. Using the formula I gave above, a 100 Ohm resistor would limit the LED current to 20 milliamps (the recommended maximum value for reliable, long term operation).
In your photo, the green things are 1/4 watt resistors. They are colour coded (coloured stripes indicate their value). Resistors also come in tiny Surface Mount packages. These are usually tiny, dark, rectangles with a three digit number stamped on them. Again, in your photo, below and to the right of the green resistors are SMT resistors (I can see R6, R9, R7 labels adjacent to each respective component).
On the Tsunami board perhaps you are looking at two capacitors (cans with a black half moon on top?). If so, they are likely 25V 100 MicroFarad electrolytic capacitors.
Have you ever done a QSI Titan U decoder installation? If not, be sure to read the Titan installation manual cover to cover. You can check polarity and continuity in a LED using a 9 Volt battery with a 1000 Ohm resistor in series. I suggest you check your polarity with that, having already isolated the LEDs from the circuit board. This will tell you what wires are common + voltage, etc..
Are the two speakers separated by some distance or are they facing each other in some A frame? The stereo separation works by having two speakers apart (your headphones are an example). You can change the balance on your headphones and the sound source seems to change location as well.
Thomas is correct about the 21 pin plug in board. However, not all DCC boosters are the same voltage output. Some put out more than 12 Volts (I assume to compensate for the voltage loss in the bridge rectifier onboard the decoder - as Thomas mentioned). Using DCC, you may actually get a higher speed than the current DC lok board allows. Ultimately, top speed is dictated by motor/gear combination and track voltage - the decoder can only lower the top speed from maximum track voltage.
Unless you have miles of relatively straight track, is it realistic to actually need a top speed of 85 Mph? Real trains have to slow from top speed for most curves and turnouts.