There is no border crossing between the two sides of SXM. Everyone at Le Petit or Esplanade will speak English. Almost everyone else on the french side will also speak at least some English and if you have some french, you should be entirely good to go. Air France is nonstop to SXM from Paris, yes. Not sure how convenient it would be, but you also have KLM from Amsterdam, non stop to SXM. I THINK that is all the nonstops from Europe to SXM.

Edit, oh and by the way, as far as Anguilla, most everyone who stays on Anguilla flies into SXM and takes the ferry over. I read in the paper the other day that they are considering extending the runway there, but that currently 90% of the people who stay on Anguilla do NOT fly in there and as far as I know, there are no other ferries going into Anguilla from other islands, so I guess most people come on the ferry from SXM.