This is from memory, so I may be forgetting:
There are a few free demonstrations, often depending on what they're highlighting that year, but also including the Eat to the Beat concerts.
There are some things with a nominal cost. (<15/per person or item)
There are some things with a more-than-nominal cost. ($45 and up)
For the nominal fee there are two different things: Seminars and Food booths.
The Seminars are done in the old Wonders of Life building (between Ellen's Energy Adventure and Mission:Space). They added a small price (which is dependent on the seminar, and there are AP and TIW discounts available if either of those apply) a few years ago because the lines were getting unreasonable. You can sign up for these ahead of time (usually starting in August - watch MousePlanet for info) or try day of or day before, if it's not sold out. For the beverage seminars, you generally get 3 items to taste and they have a representative talking about either the winery or region or brewery or whatever the 'theme' for that seminar. For culinary demonstrations they generally have a wine paired with them, the chef demonstrates on stage making the dish, and you're given a small appetizer sized version of it (that was prepared before). I really like the seminars to get a little education (sometimes not much with some of the beverages) and to taste different things. Others don't like the fact that they now charge for something that was free on the pocket book. The last couple of years before they implemented the fee, though, if it was something fairly popular, you'd have to line up an hour or more before in hopes of getting into it, and that's just not free when it comes to my vacation.
The food booths are the most visible part of the F&W fest. Around World Showcase they set up a couple dozen booths that sell generally 3 or 4 different foods (a few bites worth) and 2-3 beverages (usually wines, though they're getting more beers too), themed to each booth. I don't recall if there were any foods over $5 last year - most in the 3ish range. I did a blog post on MousePad a couple of years ago with all the food items and prices. Let me know if you want me to find that link. My sister and I (when it's just the 2 of us) generally plan 3-4 meals of 'eating around WS' during our vacation and try just about everything food-wise. We just get one of each and share. It's a GREAT way to try something you wouldn't order in a restaurant (escargot or frog legs, for example) but maybe would if you knew if you liked it. Good for introducing tweens (and younger/older kids) to new tastes, too.
The more expensive things include food & wine pairings, where you get a larger size of 3 dishes and pairings to go with; also specialty wine dinners (we did one a couple years back that was 6 or 7 courses, fully paired - we ROLLED out of that one!); specialty luncheons (we did a tequila one last year and really want to try La Hacienda for a meal some time!) and 'Sweet sunday' brunches. They also have a dessert 'reception' that we've done twice on Fridays, and the Party for the Senses on Saturday (I've never done that one). All of the info on these (and ability to register) is generally available in August as well.
Hope you're not sorry you asked!!!