Is is better to rent or to buy?

It depends on how long you’re planning to stay in France. If you’re here on a short-term basis, it’ll be easier to rent.
However, if you’re planning to settle down here, the credit rates being low at the moment and the rents rather high, it may be worth buying.

What is the role of a Relocation company?

A relocation company can help you find the right schools and home and help you with the settling-in. Two or three days of visits are usually enough to enable you to find housing.
The Relocation company will ensure all the preparation work: selection of apartments according to your criteria, organisation of the visits, accompany you, inform, advise you, negotiate the rent for you if possible, check the lease contract, do the inventory of the premises for you, set up the utilities contracts, without forgetting opening a bank account and subscribing a housing insurance.

Where to live?

If you need to find schools, it can be an option to look around the school, and not too far from your work place.
If we’re talking about the Paris area, the city will offer you apartments. If you want a house, you’ll need to go out of the city, in the suburbs, where you will have bigger surfaces and green areas for the same rent.
It may be of some interest to consider also the transports to the airports, train stations, or distance to highways if you need to travel.
The western suburbs are demanded, as well as some in the eastern.