From my understanding, mead is primarily made from honey and may or may not have hops added. Is mead considered a style of beer, or more of a wine, or a completely separate kind of beverage?
Are they brewed similarly? More specifically, would it be reasonable to think a brewery I like may make, or consider making mead as well?
Mead is not considered a style of beer, since the sugars in mead come from honey, not from the starch of a grain. Hops are sometimes added to mead for flavor and as a preservative.
The process for making mead is more similar to wine making than brewing beer. There's no brewing (boiling) stage necessary in making mead. All of the fermentable sugar comes from the honey in mead, so you just mix honey with water (and whatever spices you want) and go directly to the fermenting stage. Mead also has a higher alcohol content than most beers (8 - 20%, which is more similar to wine, or even brandy).
...would it be reasonable to think a brewery I like may make, or consider making mead as well?
Not really. At least not in the U.S. Beer is much more popular than mead, and the process for making mead is different, so relatively few brewers are going to make it. I tried mead once at a specialty beer & wine store, which is your best bet for finding it in the U.S. You may have to ask around to see if a store can order some for you.
In addition to what was already said, there's a lot of legal gray area, as most if not all states have different laws governing breweries and wineries. Mead is really something different than both, but I believe most meaderies choose to identify as wineries, and many if not all states prohibit wineries from having malt on premises, and breweries MUST use malt in fermentation. You'd either need to find someone that has a license for both beer and wine, which probably isn't that common in commercial operations (brewpubs may be your best bet there), or look for someone who makes a braggot, which is generally a beer/mead blend. Dogfish Head makes Bitches' Brew, and Sprecher Brewery just released a braggot this year. If you're looking to buy, wine shops are generally a better bet - again, lots of people don't know exactly what to do with mead, but I've had good luck finding it, usually around the dessert wines, sherry, port type of wines.
Simplified definition:
If you're fermenting grains, it's beer.
If you're fermenting fruits, it's wine.
If you're fermenting honey, it's mead.
It's not really that simple, because there are beers that use fruit (e.g., cherry lambic, raspberry wheat), beers that use honey (it's a fairly common adjunct), wines that use fruit (e.g., elderberry wine), and a whole lot of meads that use fruit. The crossover is substantial. When you consider hard ciders, it gets even more complicated (is apple wine really a cider?).
The base ingredient of beer is almost always malted barley. Even beers named for another grain — like wheat beer, oatmeal stout, rye beer — use malted barley as a base. Hops are a critical ingredient in beer for two reasons: bittering and aroma.
The base ingredient of mead is always honey. I've had mead with hops (Charm City makes one), but it's uncommon, and I personally don't like the flavor.
It's more common to find a winery that makes mead than a brewery that makes mead. There's an outstanding one in Montana called Hidden Legend. They also make a mead/wine blend called a "pyment," which was popular in the 15th century or so.
Mead is an entirely different product which tastes more like a wine than a beer but is quite distinct from either in terms of taste, designation and production. I have never come across a mead flavoured with hops but some are flavoured with other botanicals such as spices or orange peel so I cannot guarantee that none are. Most beer breweries undertake a more complex brewing process involving adding ingredients to the mash at different stages and as such, knowing a few hundred UK brewers as I do, they are all about getting the complex mixture correct and blending ingredients correctly they are disinterested in the simple mead making process. That said the mead making process; adding honey to water, adding yeast and letting it ferment may be boring to them it doesn't mean that none do, but I have never known any to be interested. On the other hand some wineries in the UK have their own beehives to help pollinate their fruit and so they produce mead as a side product. This may also be true in the US.
A quick search bears out my thoughts on wineries in the US: Where to buy Mead.
Mead is its own thing but often will be called “Honey Wine” but it is never an ale or beer. The process it’s made from is pretty much a wine-making process but there are a few differences leading to the fact that some places list their meads and honey wines together and others list them separately. Technically mead is its own category, but it’s basically a sibling to wine not beer. It’s fermented not brewed. Beer is more of a cousin to it.
Mead in some European countries is one of the stronger alcohol beverages you could get reaching 50%. (Apart from pure spirit of course) some people consider mead to be medicine rather than alcoholic beverage.
Some people might say mead is part of beer but they are wrong and confusing yeast and sugar getting fermented with actual mead. Some European countries defines mead as "The savory materials were given up by honey, carnation blossoms, poplar buds, oak acorns, juniper berries, and many other valuable herbs. Rich taupe color is reached by the use of natural blueberry, black currant and raspberry juice. This drink of great aroma and taste is of 50 % alcohol by volume"
