[nomadking]

Based upon Sephiroth's link, only £3.3bn of defence spending was attributed to Scotland. So even with no defence spending at all in an independent Scotland, that doesn't make that a significant dent in a £12.7bn deficit.
Government borrowing interest rates are connected to deficit levels.
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Higher debt interest payments. As borrowing increases, the government have to pay more interest rate payments on those who hold bonds. This can lead to a greater percentage of tax revenue going to debt interest payments.
Higher interest rates. In some circumstances, higher borrowing can push up interest rates because markets are nervous about governments ability to repay and they demand higher bond yields in return for perceived risk.

How's this for a misleading statement from the SNP.

He also said Scotland's "notional deficit" had fallen faster than the UK's in percentage point terms.

The UK figure was so low, that it couldn't drop that far in %age point terms, especially when Scotland accounts for more than half of the UK deficit.

However he accepted that in absolute terms the Scottish deficit had fallen 14% over the year, while the UK's had fallen by 45%.
He also accepted the Scottish deficit was six times larger than the UKs - expressed as a proportion of GDP - up from four times in 2017/18.

A large chunk of the need for austerity is a result of Scots one way or another. Whether it's that they account for half of the current(pre COVID-19) deficit or whether it was the excessive spending of Blair, Brown, and Darling(all Scottish).
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The Scottish deficit is the highest in Europe and one of the largest in the western world.

Any trade deals with the EU or anybody else, would no longer apply to an independent Scotland. Any deals are made with the UK as an entity, not as a specific list of countries. Access to any deals in place at the time, can't be handed over to Scotland. Just as any deal the EU makes with whoever, applies to whatever the current list of EU members is. Eg if Turkey joins the EU, then any deal applies to them as well. Eg If country X(not just the UK), leaves the EU, then any trade deal made with the EU, no longer applies to X.