We started with pears here, too. DS LOVED them!! Then we gradually added in all sorts of stuff like sweet potatoes, squash, apples, banana.
I don't think you need to be concerned with LO getting enough iron. That comes through breastmilk and formulas are fortified with it...LO is probably getting enough. Once they hit about a year old (when solids start becoming the main source of nutrition and not milk), you might need to think more about the iron amounts. But, I wouldn't right now. Milk is still the main source of nutrition and solids--at his point--are more for fun (experimenting with tastes and textures and getting the overall hang of things).
I also don't think switching food groups around will confuse him, per se. But, it might be nice to have some consistency for a couple of days so that he can get used to that particular taste/flavor.
HTH a bit!! Above all, have fun (both of you)
