Serre Chevalier and nearby resorts

Hi, I am going to Serre Chevalier for a week just before Easter.  I
understand from the Serre Chevalier website the lift pass gives access
to the resorts listed below:

Grande Galaxie: one day pass free at:

    * 2 Alpes,
    * Alpe d=E2=80=99Huez,
    * The Milky Way (Montgen=EF=BF=BDvre, Sestri=EF=BF=BDres, etc.)
    * Puy St Vincent

I would appreciate comments about how practical it is to travel to and
ski in these other resorts.  Is there a good bus service,or is it
better to drive?
Does the existing lift pass work in these resorts or do I need to go
to the lift pass office to get a pass for any particular resort.
In particular I would like to go to the Milky Way, is it best to enter
at Montgenevre and then ski to other resorts?  Does the Milky Way link
together well.

Thanks in advance for any help.
Regards
Brian