Hi Joy,
I would recommend the
RER B from CDG T1 to Paris with only one suitcase and child in tow. Keep in mind that Metro turnstiles are wide enough for the average person to pass through. Extremely large suitcases are better suited for suitcase pass-through slots which can be found at many turnstile barriers. If one is not available, there is often a special gate for handicapped and wheelchair bound travelers that opens very wide. Just be very patient if you decide to use this type of gate: it swings open after at least 5 seconds of waiting, which can be disconcerting if you haven't used one before.
Finding the CDGVAL shuttle train within CDG Terminal 1 is simple: the path is well marked with many overhead signs. And Terminal 1 is round and not massively long like Terminal 2, so it should only take a few minutes to find your way.
Chatelet Les Halles has many escalators from the RER train platforms. If the first stairwell you come to doesn't have an escalator, just walk further down the platform till you find one. Once you've arrived at the main (still underground) level, you'll have to follow the overhead signs towards Metro Line 1 (yellow color). It may be extremely busy inside, with people crisscrossing every which way, but it's no cause for concern: this is daily life in a metropolis such as Paris. Remember that your ticket for the RER B is good for the entire Metro ride as well. You'll likely have to use it multiple times within Chatelet Les Halles to get past turn stiles on your way towards Metro Line 1.
You'll want to follow signs for Metro Line 1 which also mention the name "La Défense". This is the direction you'll want to take Metro Line 1, which will pass by the station George V.
If you decide to use Les Cars Air France, it's easy to get to George V station from Arc de Triomphe (which is station
Charles de Gaulle Etoile). Simply enter the Metro station at the Arc and take Metro Line 1 towards Chateau de Vincennes.
I wouldn't recommend shuttle buses. They're no fun. And more expensive.
Best regards,
Ben