Welcome! It is incredibly intimidating in the early years when you realize that your children aren't just a bit bright. I found those early preschool/baby years the most daunting, since it was clear that my kids were different but not clear how that would look in school.
Even without any added layers of verbal inquisitiveness, a three-year-old and a baby are exhausting. It's a season of life that takes a lot out of you, but this too shall pass. Like Portia, our kids started having Quiet Time as soon as they stopped napping, and it was a good time for everyone to recharge, even the kids.
I'll add as well that I've watched my younger son develop and learn even faster than my oldest, who is already the talk of the school and the best in all areas. Yet, I've found it easier with my younger one, because I already know what works more or less, which battles to fight for, and what to let go. They have each other, too, so my boys will quiz each other with math problems, or my older boy will help the younger one.
Having an even brighter little one doesn't necessarily mean a repeat of your experience with your oldest. Our youngest is an introvert and demands much less social interaction than the oldest.
Try to carve some quiet time into your day. Set boundaries, even with your baby, for sleep. You can use their abilities to your advantage and teach them to read a clock early on.
While you're in the busy baby season, let your worries go about the future. The problems a three-year-old has behaviorally or socially may be resolved by school age, and new issues may arise. My older boy had some major transition issues as a four-year-old, and our wonderful school made a plan for helping him adjust to the next school year. He somehow matured over the summer and came into school after the two month break as one of the most mature kids in the class. Solve the problems you have now, and avoid anticipating problems.
It does get better. Much, much better. Particularly when the kids are old enough to get the TV on in the morning when they wake up at 6 a.m.
