How do you juggle between doing what you love at work and spending time with your children?
Have a schedule. Go home for dinner. Incorporate kids into your social activities - take them out for dinner, or do what you want to do and bring them along. Block off time on weekends to just be with your kids and family. You can also optimize your schedule, where for example you'd be chopping vegetables for dinner, while the kids are eating breakfast.
How do you hire a part-time nanny?
Put ads on all the places that accept ads for a nanny. When you work full-time it is easier because you need a nanny for full-time, it's harder to match up with a part-time nanny. Talk to them, find someone with experience, call their references, and try to hear how they hang out with kids and what the interactions are like. There will be tradeoffs and you might want to have backup child-care, like grandparents. Preschool is a great way to keep your keets out of home.
Do you change as a person after you have kids?
You might get less interested in novel experiences. Traveling to a difficult place, for example, would take 2-3 times work more. You hit some kind of boring middle-aged mentality where you want to do one more active thing before you get old and die. You also spend more time thinking about big-picture life events.
How do you rest as a parent?
Take turns with your partner. Get enough sleep when you need it. Go to bed earlier. Get a nanny if you can afford it, have grandparents help out. Get all the help you can get, you would need it. If you have friend who have children just like you, swap playdates. It is easier to take care of a group of children when they can play together.