5 year old MacBook, I've never calibrated my battery.

I've had my MacBook for five years and the battery still seems to function fine, however I happened upon this article out of an interest in the best way to take care of my battery and now I'm wondering:

1) Is it too late for me to start calibrating my battery?

2) In the instructions for calibrating it tells you to wait till your computer goes to sleep- does that mean I should turn off the automatic sleep timer? (of course that only comes on if I'm not using my comp so I guess I would just have to keep using it, right?)

3) I get a warning that pops up when I'm down to about 10% battery life that says "you are now running on reserve battery power." Does that Interfere with the natural going to sleep that is supposed to occur? Because I think I read in this article or maybe another thread that it's the reserve battery power that the comp is using when it goes to sleep: if that's the case, am I using up the reserve that it needs and should be using only in sleep mode, or should it still be able to go to sleep even after this message pops up?