Hi D. - I just wanted to encourage you. A good friend of mine has children in Duncan Creek Elem and they love it!! All four of her children have gone there with the oldest now in middle school and the younger three still at Duncan Creek. They have had a very positive experience! I've only heard good things about it!
We're sending our 4 year old to North Metro First Baptist Church's kindergarten this year b/c it's a half-day program instead of the full-day public school's do. If you'd like info on that program, let me know. If not, I'm sure you'll be pleased with Duncan Creek.
Trilogy Park is a beautiful subdivision - I hear great things about it! My husband & I didn't know about it when we were house hunting and wish we had. We've said that when it's time to move we would love to end up there.
As for a non-denom Christian church, I'd love to give you a great option. We actually drive a little ways south to attend Stonemill Church. It's off of 85 and Old Peachtree. We were attending a little church nearer to us but found that Stonemill was a better fit. It is loosely affiliated with the Southern Baptist Convention but feels very non-denom. If you're interested in giving it a try, their website is stonemillchurch.org. If you plan on visiting, email me and my husband & I can meet you and show you around. They have a great children's ministry!! I have two boys 4 & 3 also - five in July and 4 in October - as well as a 10-month old daughter.
There is a brand new parks & rec type park under construction down the street from you on Braselton Hwy. It's supposed to be the best in Gwinnett County once it's done. I haven't been up that way in a couple of months so it may be nearly done by now. There's also a fantastic nature trail-pond-playground-type park off of Pine Road and Hog Mountain called Little Mulberry Park - it's actually not "little" at all. It's huge & extremenly nice! The playground entrance is at a different location but you can do the nature trail from Pine & HM and get a map for the other playground entrance.
There's also a new "kids village" off of Auburn Road (Hwy 324) that has a Swim Atlanta, a Monkey Joe's (an indoor playground type place) an outdoor playground, a Ben & Jerry's and a few other kid-friendly places. We've got our boys in swim lessons there.
Hope that helps! Welcome to the area!! Send me a message if I can help further. May God bless your new life here!!