Thing is, it *can* be done (I'd do it if I was forced to (eg. collapse of civilization, alien invasion, etc) - but because I don't know the OP's level of expertise, I'm not comfortable going into any detail as there are a number of factors (and their consequences) to be familiar with.
This is not true. Many have done this during shortages and some have used different primers when loading hot rounds to meet certain power factors(don't recommend it).
As mentioned, not something you want to do without some experience at the bench and willing to risk some injuries. Lots of research should be done to find a starting point before even attempting it. Even then, just cause it worked in Joe Jacks super custom open class 1911 doesn't mean it will work in yours.