Sentence structure: preposition + wh- clause

#1A is potentially acceptable, though "it's a question" might be more likely instead of "it's the question."
#1B is ungrammatical.

#2A and #2B are ungrammatical.
Try "No matter which you choose, you will regret it."

How about the following underlined sentence? Is it still wrong or awkward?

It is no matter of what you choose. I can buy you everything that you want.

It makes no sense to me.

Then, how about "No matter when I get a chance, I travel abroad?" Is it right and natural?

That's unnatural. Try, "Whenever I get the/a chance, I travel abroad."

Then, could you tell me why "No matter when it starts, that democracy is a long, slow process of negotiation" is right? I extracted this sentence from 'nytimes.com' and I think the structures of this and the above one are almost the same as each other.

The contexts are different. Your sentence is about routine/habitual/repeated actions, whereas the sentence you quoted from the New York Times is about a single event.

1. Then, how about "Whenever it starts, democracy is a long, slow process of negotiation?" Are both of "Whenever ~" and "No matter when ~" okay in this context?

2. How about the following ones? Are both of them also okay in the context of each one?

No matter where you are, you will always be in my heart.
Whe

lucas21c1. Then, how about "Whenever it starts, democracy is a long, slow process of negotiation?" Are both of "Whenever ~" and "No matter when ~" okay in this context?

I prefer "no matter when" in that context.

lucas21c2. How about the following ones? Are both of them also okay in the context of each one?No matter where you are, you wi

Thank you very much for your help. This might be a trivial question, but could you confirm whether "No matter when it starts, democracy is a long, slow process of negotiation" is okay as it is? Or, should it be "No matter when democracy starts, it is a long, slow process of negotiation" or "Democracy is a long, slow process of negotiation,