There's fifteen reserved powers (defence, foreign policy, social security, financial and economic matters, employment, constitutional matters, immigration & nationality, monetary system, common markets, some transport, data protection, energy, gambling, medical ethics, equal opportunities).
These are all important and there would be some gains for iScotland (defence, constitutional matters, transport, arguably data protection), but the most important ones- social security, financial and economic markets, immigration and nationality, monetary system and the common markets, maybe even some areas of defence, would still be largely controlled by Westminster in the SNP's current plan, because they would be the dominant partner in the currency union
Again, assuming everything you say is correct then Scotland would have complete freedom of choice, within parameters negotiated with other nations. This is still more freedom than we have at the moment.
And of course, a Yes vote does not equal the SNP running the country. Different parties would have the freedom to make different decisions, cooperate more with other nations and enter into more shared agreements, or conversely disengage from other agreements.
A currency union is the SNPs preferred system on independence day, and it makes a lot of sense. However, 5/10 years down the line when things are more settled an Independent scotland could easily choose to leave the currency union.
A Yes vote indisputably (I know you will though
) gives Scots more choices for ever. A no vote ties Scots into choices being made for them by another country for a very long time, if not ever.