Super Bright Red Led - BC547B Transistor, but which Resistors?

That'll work.
2 LED/resistors in parallel per outpin will work fine too.
(5V - 2.3V - 0.7V)/100 = 20mA (0.7V is Vce across the ULN2803, rises to 0.9V typical at 100mA)

How are you making them touch sensitive?