Yes, the gel and everything that roasted with the chicken goes into the stock. If I don't have any homemade I use bouillon cubes (I found a robust variety a while back and bought a lifetime supply). I have some beef bouillon in the fridge also. That can help boost the cooking liquid when starting out to braise a pot roast or make stew.

More than once I've seen people mentioning burning off the alcohol in wine. Why? It adds more flavor to whatever you're cooking and is gone by the time cooking is finished.

This evening I made teriyaki chicken, that I haven't made in probably years. Here in the states one of the earlier cooking programs on Public Broadcasting was with Jeff Smith, who was The Frugal Gourmet. Alas, his program disappeared from sight when he was charged with abusing the young man who was his assistant, but his teaching of how to make dishes was top-rate and I have a number of his recipes I still use. And his cookbooks are out there in the used book stores. I gave one to my son, and explained that while the man himself was in disgrace, his cookbook was helpful in teaching how to do the things needed for various recipes.

1/2 cup of sherry (though I didn't have any so used Marsala)
1/4 cup of soy sauce
2 tablespoons sugar
grated ginger (as much as seems right)

Pour the marinade over the chicken and let it sit for at least a few minutes; I turned it every so often and left it in the fridge for a couple of hours.

I usually use cut up whole chicken parts in the past, but on this occasion I had a deeply-discounted package of organic chicken thighs that had been deboned and no skin. I buy it frozen. Normally skin and bones go in the dish, but when the thighs were half-price to start with and if you bought two you got the second package for 1 cent, I got them. And thighs have so much more flavor. Anyway, use peanut oil if you have it and put enough in a deep skillet or a other lidded pan to brown the chicken. Do it in a couple of batches if needed (I had about 3.5 pounds of meat, so it took two batches). Once it is browned, return all meat to the pot, pour the marinade over the meat, cover it and let it cook for 30 minutes. Serve over rice.

Because I had as much chicken as I did I made half-again as much marinade to work with. And I'll have some wonderful leftovers for the rest of the week!