Where can I find the keys for the locked doors on the first floor?

Solution 1:

Basement Key

The key to the basement is located inside of Sams locker. The combination is found in two secret panels in the house. The first half of the combination is found on a secret panel directly across from Sams room. The second half is found in a panel in the downstairs hallway, across from the closet containing Sams list of things to buy from the first day of school.

Lobby Key

The door in the lobby doesn't have a key. You actually need to get to the room behind the door using a secret passage in the basement, which will already be opened. Once inside the room you can unlock the door from the inside.