It sounds like time for an overhaul, and your husband needs to be included!
I can't tell you exactly what your bedtime routine should look like, but I'll just pitch in a few ideas. Perhaps they will work, or maybe someone else will have a better suggestion for you.
My first step would be to start bedtime much, much earlier. Say, 6:00 at the latest. Kids need plenty of sleep, and it sounds like they could be wound up/overtired, which makes them act more manic and harder to keep in bed. Especially if they are not getting a nap. Most of the preschool teachers I know recommend a 7pm bedtime at the latest.
Second, I think you might be getting hooked into some delaying tactics: "Mom I'm hungry/thirsty" is one we hear often. We are very clear with our son that dinnertime is dinnertime, and that's it for food for the evening. If your kids like a cereal snack before bed, make sure it's a more 'grown up' higher-fiber cereal that will fill them up instead of a sweetened kid cereal. Sugar/cane syrup (and any corn syrup or food colorings/additives) will also make them rev up, so it's another reason to avoid it. When you close the kitchen *there's no going back*, and you have to mean it. "You've had your snack, now it's time for bed." or "This is not a snack time. You had a time to eat. Go back to bed." Being consistent is hard sometimes, but you must be firm or you will have years of this arm-twisting. In short, they are getting up because you are accomodating this.
Third, talk to your husband about what he can do to help. Is there anything that you are doing that he *can't* do, like, say, nursing baby? Once you have established which jobs are "mom only", then Daddy needs to step in. Can he be brushing teeth, or helping with pjs, or reading a story to the ones who are waiting for a turn with you? (When I was a toddler group teacher, I had to work up plans like this with my coteachers for more attention-intensive activities like diaper changes or naptimes.) If you and your husband can come to the bedtime routine as a team, it will be better for everyone.
No More Screaming. Your preschoolers are old enough to understand using their quiet voices at night. As I said before, they sound overtired, so an early bedtime (especially at preschool age) is necessary. This said, I would also find one place in the house kids may go to scream. The basement? The pantry? Someplace that's not a punishment. This is so the children will have reference for later. "We save our screaming for the basement when it's playtime. This is a quiet time now." During the day, do they usually yell for you, and are you in the habit of coming to their call? This is something to consider. I had a preschooler a while back in my group who, when he started, would just sit in one place and literally scream across the room at me, and after a week of this, it occured to me "Oh, this is what works for him at home!" I put the kibosh on this very quickly by firmly telling him that "if you want to speak with me, you will come over to me. Screaming does not work." After this, I simply ignored his screaming my name, and when he did come over to me, I addressed him as if nothing had ever happened, giving the negative behavior no attention at all. This habit of his changed remarkably quickly.
As I said before, I know there are other facets to making bedtime more pleasurable/less hellish. I don't have any perfect formulas, because every family's needs are different, but from what you were describing, these areas might be good places to start problem-solving around.
Best of luck-- kid can be so tough on us!
H.