Again I pretty much agree with you except for the comment about inflation. To my understanding, inflation is caused directly by central banks increasing the supply of money in the economy causing its purchasing power to decrease. I believe all Western countries have a central bank in operation so the idea of governments using public spending and other policies to influence the inflation that they themselves have created seems spurious.
Inflation in the UK is measured using the Consumer Price Index (CPI). These are the increase/decrease of the 650 most common items households will purchase. Using this you can see how peoples spending will be affected year on year. So if I left £100 in cash for a year, it would allow me to purchase X% less or more (if minus inflation) on average a year later.
This is important because for your investment/gains to be profitable, it needs to beat inflation for you to actually buy more. If inflation is 2% and your investments yield 2%, in essence the numbers are just bigger - you won't get more for your money.
There are a few ways to control inflation, and it revolves like you said about the amount of money in circulation. If you want to reduce inflation, supply and demand dictates you need to restrict the flow of money - you can do this by increasing things like interest rates and VAT which would put people off spending money.
On the other hand, if you want to increase inflation you want people spending money - so as a disincentive for saving you reduce VAT (Value Added Tax - applied to virtually all goods sold as a %) and decrease interest rates. This puts more money in circulation, as there is more economic activity due to buying and selling.
VAT, Interest rates, Inflation, Employment %, Stamp Duty...etc are all used to balance eachother out.
Central banks can print more or less money, but they control this to prevent rife inflation as it's unsustainable and can cause another recession if it gets out of hand.
Inflation isn't bad, as it signals growth of an economy providing it's stable growth.