As to perching, I started out with a perch that was practically on the cage floor at 7 weeks. Once she got the hang of that I added a couple more perches, each a little higher than the other. Yesterday she blew me away when she climbed to the top of the cage. I was so scared!
Can't offer advice on the stepping up as I haven't really been pushing the issue with Loki yet but with my Cockatiels and conures and such, it seems to come natural to them once they are perching regularly.