Excellent set of advice!
I think #1 is sometimes the tricky one. Many think 'everyone' can write, but it's just not true and many people continue to delude themselves that they can -- perhaps even me.
I picked up Samuel Delany's book which I ran across yesterday (I'll start a separate post) but in the first chapter he talks a bit about 'talent' which is what I think she is saying in point #1.