হাঁপ ছাড়া

No, it is neutral to informal. For formal writing, use 'স্বস্তির নিঃশ্বাস ফেলা'.

Only if you are describing the relief *after* the exercise is finished, not the act of panting during it.

They are just spelling/pronunciation variations of the same word meaning 'gasp' or 'pant'.

Technically yes, it means 'to relieve someone else,' but it's much less common than the standard form.

Yes, it is equally common in both regions.

Usually no. It's specifically for the relief that follows *stress* or *worry*, not just any happy moment.

You can say 'আমি অবশেষে হাঁপ ছাড়তে পারলাম' (I was finally able to breathe a sigh of relief).

Only if used in the wrong context, like being relieved about someone's misfortune.

A good opposite would be 'হাঁফিয়ে ওঠা' (to become breathless/stressed) or 'চিন্তায় পড়া' (to fall into worry).

You can use it *after* the interview to describe how you felt, but don't use it *during* the interview as it's a bit too casual.

People often just say 'বাঁচলাম!' (Saved!) for the same effect.

Yes, many modern Bengali songs use it to describe emotional freedom.