The old Century I have from Grandma had a lot more of that white powder than yours. The water was super cloudy and the cap was cracked. The cloudy may have been from the bad cap. The goo was bad and full of bubbles, the flow was not so great. I tried to clean the powder to see if it would help. It was stuck to the solid wax bottom and flushing out the cold lamp did not do anything to remove it. I heated the lamp with distilled water in it and the powder went away/dissolved. But the goo was still toast. My experience is very limited, but I would say leave well enough alone. Grandma ran that Century all the time for decades and I think the powder is a byproduct of the wax breaking down. I don't think getting rid of it will stop or reverse the damage. You probably have a lot of good life left in it, and I must also say the gold anodizing and cap paint are a lot less faded than what mine was. Looks good.
great flow on that lamp for sure! it seems to happen to lamps that are stored for a long time. at least in my experience. i don't think it will affect the flow, but it may start breaking off and entering the wax. i am not entirely sure. does it stick to the glass when the globe is hot, or is it stationary?
since it's stationary, i'd leave it be, especially given how nice the flow is. the process of removing it from the globe may cause other issues like cloudy fluid.