[...] pulls resources (employees, production, etc) from other parts of the economy, increasing the costs of the remaining resources since there's less available.
That is why I specified that there needed to be excess productive capacity for whatever they are buying. As long as the economy is not at full employment, the government isn't bidding up the prices with its spending.
At full employment though, you are absolutely right.
There actually isn't such a thing as a "natural rate of unemployment", so all of those 4% are part of the excess productive capacity.
If those people are unemployed simply because their previous contract expired a bit before their new one started (frictional unemployment), then I agree it is totally unproblematic. If it is because there aren't enough jobs going around (structural unemployment), it isn't.
All money in monetarily sovereign countries come from government spending: It is spent into existence by the central bank marking up the reserve accounts of the banks of the people and businesses it pays to. The money in circulation and saving is simply the difference between total government spending and revenue. It is important to realize the order of operations here: The governments has to spend before it can tax, or else there wouldn't be any money to tax.