Yes, if only questions of economy could be so easily answered. But of course, medieval economies weren't run primarily on coin, they were a function of land, serfdom and vassalage (for those who weren't nobles).
That's true out on the manor--but on the manor, there really isn't any commerce going on. A blacksmith and maybe one or two other businesses that support the manor, but in general the occupations on this list are all happening in towns and cities. (And, incidentally, all of these occupations are filled by like 5% or 10% of the population.)
The towns and cities are largely outside the feudal system. They exist where the lord has granted a special charter exempting the townspeople from vassalage. So vassalage isn't really relevant to most of the people in these occupations. Barter may be common, but so is coinage.
As for incomes, Balesir is dead on: It's a tough one to nail down when "medieval" refers to a 600-year period over an entire continent. But here's a generalization for you: Merchants and masters at tradecrafts have the potential to make some real money and form what we now think of as the middle class. Everyone else is pretty much existing in a subsistence economy. Meaning they make roughly enough money to get by.
Those who make substantially more probably do so more due to non-occupational factors (they happen to be the only wheelwright in the city) than to their choice in occupation. In other words, it's not what you do that defines your income, so much as the local supply-demand ratio for that particular occupation. (There are exceptions, of course--some occupations are perpetually in demand. Particularly if they require high degrees of skill and are regulated by guilds.)
So for your campaign world, figure out what it costs an average townsperson to support his family (including apprentices and servants). Most tradespeople probably earn a little more than that. Some chunk might earn another 25% due more to circumstances than their specific occupation. Same for key trades (like stone masonry in the medieval world). Well-connected merchants, and masters in their trade might earn 50% to 100% more, and are likely to be the political movers and shakers in the town as well.
Like, basically what he as a DM uses, I gather. Again, IIRC.
