I found the problems and fixed them:
1)- Some libraries needed:
Note: I also had some libraries that were not compatible with UNO. I had to remove them. I forgot their names.... but what I found online about this was somewhat misleading or unclear.
Note: UNO has only TWO hardinterrupt pins, but any input pin can also be setup as interrupt through Soft-Interrupt.
Example in my application:
PCintPort::attachInterrupt(9, IntLevel1Up, RISING); // Attach all the interrupts to relevant pins
PCintPort::attachInterrupt(10, IntLevel2Up, RISING);
PCintPort::attachInterrupt(11, IntLevel3Up, RISING);
PCintPort::attachInterrupt(12, IntLevel4Up, RISING);
PCintPort::attachInterrupt(13, IntLevel5Up, RISING);
PCintPort::attachInterrupt(13, IntLevel5Up, FALLING);
2)- I had some syntax errors with things like " } "
3)- I had multiple detection for each interrupt (electrical and/or mechanical bounces) and my code was not immune to that: fixed.
4)- TRUE, I may not need interrupts for my application as the uP is fast enough, but interrupts provide more info since you detect a ONE TIME event, and can differentiate FALLING from RISING and do different things accordingly.
Also. if you have waiting loops or routines that take time, digitalread could miss an event short enough (my events are detected only 4 times per loop by digitalRead). Interrupt will not.