از دیدن شما خوشحال شدم.

Yes, absolutely. It's the perfect way to end a first meeting after you've used 'khoshbakhtam' at the start.

No, that's too informal. Use 'didane shoma' to show proper respect.

In Persian 'Ta'arof,' you say it anyway! It's a social requirement, not necessarily a literal report of your feelings.

Yes, it's a very common way to end a polite email: 'Az didare shoma dar hafte-ye gozashte khoshhal shodam.'

Persian views the meeting as a completed event at the moment of goodbye, so the past tense 'I became happy' is used.

Yes, but change the verb to 'shodim' (we became) if you are speaking for your group, or keep 'shodam' if just for yourself.

'Khoshbakhtam' is 'Nice to meet you' (start), 'Az didane shoma khoshhal shodam' is 'Nice meeting you' (end).

Say 'Khoshhal shodam didamet' (Happy I became seeing you).

Yes, though they might prefer 'Az molaaghat-e shoma khosh-hal shodam' or 'Khosh-hal shodum'.

Yes, 'khosh-vaght' is slightly more formal and very common in business.

Not at all. It sounds very polite and well-educated.

People will understand you are a learner, but they might think you are in a rush to leave!