I somewhat concur. If reading that the way you are indenting (I having had any coffee yet this morning!). The biggest thing I don't think I agree on is the old water.
Granted, if you are upgrading from 1 tank to another and moving your fish, then yes I think you should move at least 50% of the old water, if nothing else the fish are used to that water. If just cycling a tank then I would say no because the good bacteria doesn't really exist in the water itself and there could be more bad stuff in it than what the bacteria needs. Granted, if you are moving a bunch of stuff that already had bacteria on it, the cycle could be really short or almost none. I would still throw some kind of source in there just to check.
Also, I was speaking in general terms before. Just because you don't have an ammonia source doesn't mean the bacteria will die off right away, it will take a bit of time (I don't know how long, but we are talking weeks). So you don't have to be urgent about it.
Another thing to remember with upgrading is even if you move everything from say a 20g tank to a 75g tank, you can't add livestock up to the point of being full in the 75g tank because you still have to give time for the bacteria to get used to the higher load, that is the reason why people are told to add only a couple fish at a time.
Sorry for being long winded!