If so, how is the altar set up in Zen? Do Zen Buddhists use a butsudan or altar? What rituals are performed at the altar? Etc...?
Well, I cannot even speak for all Soto Zen Buddhists, let alone all Zen Buddhists, however ...
Traditionally, in Japan, there is a home altar, but the emphasis is decidedly on "ancestor worship" (for want of a better term) for dead parents and grandparents who are in "transition", although that is not the only symbolism in the altar. Here is a description from the official Soto-shu page in Japan ...http://global.sotozen-net.or.jp/eng/com ... altar.html
As far as I am concerned, any Buddha or Bodhisattva Statue in a quiet corner of a room can be an altar. Incense optional (it can cause cancer like any secondary smoke, or at least, trigger allergies). Since our core Practice is Zazen, it is good to just have the altar in the room where one sits. One could also do other practice in front of the altar, such as reciting the Heart Sutra, the Four Bodhisattva Vows, Metta (a South Asian practice we adopted in our Sangha) and such, but that is up to the individual's feeling.
Now, when I say "Buddha Statue in a quiet corner of the room", I would like to emphasize that such need not be what we might think of as a "Buddha Statue" ... for in what form, and in what corner, is a Buddha limited?
When I do ceremonies, I usually grab anything that strikes my heart ... As a personal Practice, often when I lead a ceremony or sitting for a group, I replace the Buddha statue on the altar with whatever comes to mind ... sometimes a car tire, a dirty diaper, a trash can, an open space, a flower, a rock. Other times, I just bow to the statue that is there. Once, after the Afganistan war started, I replaced the statue with 3 photos ... Mother Theresa, George Bush and Osama bin Laden. That really upset some folks in the group (admittedly hard to see "Buddha" sometimes).
But, you know, what isn't the Buddha, where is Buddha not found? And for me, if you think I degradate the Buddha by replacing him(her) with a trash can, or that I raise up the trash can in praise, you miss the point I think.