In the future, please ask questions about different issues separately. I'll be happy to answer these anyway, though.

1) You should use CharacterController.SimpleMove(Vector3.right*speed) instead of changing transform.position directly. The character controller takes collisions into account while direct modifications of transform.position will be carried out regardless of collisions.

2) First of all, make sure your player character has a Rigidbody attached. Then, you could try attaching a box collider to the player character and adding a section to your script that uses the OnCollisionEnter or OnTriggerEnter function (which should still be activated even if your character is passing through the object). In that function, you can add a line to set the player's forward speed to zero when it detects a collision or do whatever else you want it to do when it encounters an object.