Should Scotland be an independent country?

That may be true, but it's irrelevant to this discussion. Scotland is part of the same small island as England and, for all the faults of our mutual history, acceded to the union voluntarily, so the rule of Scotland from Westminster is neither 'imposed' nor 'from afar' in any common meaning of those terms.

'Voluntarily'?

In the sense that an unelected clique of landowners and lords got together having bankrupted both themselves and the country and performed the merger without the consent of the population at large to save their own privileges?

That they then followed this up with what can only be described as cultural genocide in forcibly clearing people of their lands, burning houses and putting them on ships to the colonies where they were then used to displace other vulnerable people is pretty indicative of how 'voluntary' it was.

I'm also curious as to how you're arrived at the declaration Salmond was only acting in self-interest? Surely he could do all these things as he likes now instead of quitting?