Pineteam,
The A/Thr interacts with the vertical flight guidance modes. If the THR Lever is in the CLB detent the A/THR mode changes to speed/Mach mode at ALT *. So it's not possible to have ALT mode and THR CLB simultaneously.
TOGA thrust is a fixed thrust setting ( I.e. A/THR is armed but not active), so no thrust reduction will occur at VFE and over speed will occur.
I'm sure Vilas can explain this much better than me though!