Ale or Mead?

It's always important to do research for a novel, especially for a historical novel. A few weeks ago, in one of my writing classes, my professor was reading a chapter of my current writing project, a YA novel that takes place in a medieval-type world.

My professor noticed that I had said that my main character took a swig of mead, and kindly informed me that more than a few sips of mead would knock a normal person out. Who would have thunk? Not me apparently, because I don't live in the middle ages, and didn't do enough research. Since I didn't want my character to get drunk, (it is YA, after all :), I changed the mead to ale. I probably have more cultural oddities like this in in my novel, but now I'm on the hunt to get everything right, even the drinks, because readers will catch it, and then will want to kill me!

Some other interesting things I learned while researching/editing parts of this novel:
    -They don't say 'okay' or 'alright' in the middle ages. What else can you use for those expressions?!
    -People back then used animal skins (bladders) to hold water while traveling. Yum
    -Peasant houses were made from straw and mud.
    -Nobles didn't eat raw fruit; it was seen as unhealthy and unsanitary. No wonder they didn't live long...
    -The crossbow was invented in the early-ish middle ages period.
    -"You dried neat's-tongue" is an insult Shakespeare used. Your guess is as good as mine of what it means.