Not necessarily that easy. I thought the French leagues had tightened up how many non-JIFF they could have on the pitch at any one time. Worth having a Marchant or LCD in your ranks (especially as you won't lose them to England) but a Lawday (or Beaumont, for example) is easier to find a French equivalent.
Can't see the likes of Lawday dropping down to Pro D2 or going to Tel Aviv.
Yes this is a very important point much overlooked in the MSM and therefore also by many fans. Mark Evans (previously of this parish) was on one of the rugby podcasts (probably the Times (which is a decent listen providing that Stephen Jones isn't on it)) a few months back and he pointed out that the fears of a mass exodus of players from the Prem just wasn't at all likely. There is a limit on "foreign" players in France, USA and Japan. NZ, SA, AUS all have enough of their own and ours are no better and the salaries aren't great. The Celts are desperate to keep as many of their own players playing for them.
We are not, unless there are major changes, going to see a mass exodus of the "good club players" abroad. No one else has the money or desire to pay them lots more than the Prem already does.