Around the Jewish Year

I have celiac. In recent years, gluten-free matzah has now been made available. I'm somewhat confused: leavening is caused by the gluten, so how can I observe the mitzvah of eating matzah on Seder night by eating matzah that can't become leavened?

Do I need to separate terumot and ma'aserot from horseradish (chrain) with a blessing?

My workplace is not particularly observant, so the religious employees take off on Pesach. The reason is primarily because our work, which involves raising insects (for agricultural research), requires handling a substrate that is possibly chametz. The mixture consists of sugar, yeast, water, a little bit of acid, and bran. Is this actually chametz? What should we do? Some of the employees are resentful that their religious coworkers "can't work" on chol hamo'ed, since this prevents everyone else from taking off during that time. In short: is it permissible to work on chol hamoed Pesach at this place?

Here are answers to clarifying questions:

• Was the substrate prepared before or on Pesach?  Before Pesach.
• Is it wet or dry?  Wet
• Is it edible?  Not in the least. Not even fit for a dog. The larvae (of the flies we cultivate in the lab) feed off of it.
• What is done with the substrate?  We place the fly eggs in it, and the larvae that develop from them feed off of it.
• Is the yeast synthetic or from barley?  They are beer preserves.
• Is the bran free of wheat kernels?  Yes, it consists of parts of the shell of the wheat kernels, but it does not include the kernels at all.

I'm performing my national service at the Science Garden, and we are planning an activity for Pesach about trees, burning, and renewal. We would also like to hold a workshop on sprouting seeds. Is it possible to sprout legumes (beans, hummus, lentils, peas, etc.)? Are legumes forbidden only to eat, or are all the prohibitions that pertain to chametz apply also to legumes?

Is it permitted to those who avoid legumes (kitniyut) to eat watermelon and pumpkin seeds on Pesach?

We went for a nature hike and the kids gathered sheaves of wheat. Is it permissible to keep these sheaves for decoration, even during Pesach, or is it considered chametz gamur? What should we do with all the sheaves?

Are we supposed to sell products what include wheat protein or wheat flour (soup mix, for example) with the chametz?

Does one fulfill the obligation of maror grown hydroponically?