You are wrong.
Haste increases max AP by 4 (8 if GC) and recovery AP by 3 (6 if GC). (You're correct regarding Recovery AP being +6 under Haste.) Thus, haste will
never cause you to max out AP, with or without GC, unless you were maxing out AP per turn without haste anyway, since the bonus recovery AP is
less than the bonus max AP.
You are wrong. Haste increases max AP by 4... and still by 4, even if GC. So it is possible to "waste" AP with Haste, because 6 is more than 4. However, as long as your max AP is at least 2 more than your recovery AP, this is avoidable. You generally want a larger buffer than that, however, so that you can save 1 or 2 AP from previous turns without wasting them; having a max equal to recovery +3 or recovery +4 is usually best.
