I wont advice you to open them yourself.Contact esanthosh or faheem.They may have some experience.If you plan to open them yourself use hair dryer to soften the glue.AT YOUR OWN RISK !
Good Luck bro. Open them only if you don't have any other option.If I am right there is TE member "titana" who works on such stuff.Contact him.
Doubt it. Is it a paper filter or a metal mesh? If it's the latter, have you tried using a pin to lift it up (or just take it out and then push it in)? May require lot of patience considering the fragile housings of R50, but may work.