Public spending in an independent Scotland could continue to grow. This does depend on sufficient growth in the economy after independence.
if the Scottish economy grew fast enough after independence, then it could increase public spending and reduce its deficit. If it doesn’t, there would be choices between a larger deficit (and so, the independent Scotland’s debt increasing faster), reduced public spending, or higher tax. The report doesn’t rule out an independent Scotland leaving the pound, but says it shouldn’t happen overnight
“The Sustainable Growth Commission recommends that Scotland keep the pound “for a possibly extended transition period”. Moving to a new currency would be “based on a governance process and criteria set out clearly in advance of voters making a decision on independence.” While still part of the pound, Scotland wouldn’t be able to set its own monetary policy (things like setting interest rates), which would still be done by the Bank of England.
Any transition to an independent currency would require a “financial infrastructure” to be developed, and happen when it was “appropriate for the Scottish economy”, according to the Commission.