Does the iPad offer a separate login for young kids that is similar to Kindle's Free Time app?

No the iPad is strictly a single user device. You can restrict some features via the settings -> restrictions controls.

No, but there are some apps that have different profiles for each user. For example, FREE McGruff SafeGuard child-safe browser has an upgrade feature that lets each person in a family have a different profile for browsing (as well as recording which websites they visited, etc.). Available at the app store - McGruff SafeGuard - or visit www.gomcgruff.com/browser