French Expat in Thailand (Bangkok)

May be only French can reply to this one. Quite specific case..

1. As an expat in Thailand, what is the best way to deal with Seurite Sociale (maladie, prevoyance), Retraite (et retraite complementaire). Should I go with local insurance but keep french retraite with Caisse des francais de l'etranger?

2. After declare income tax in Thailand. What do you have to do with declaration des impots en France? Do I have to send any justificatifs to France?

Thanks