Not yellow hatter, but am able to shed some light:
1. Current CG helo's have the ablity to DF on 406mhz, as you know the various mks of Seaking can not. However this isn't the end of the world, as all 406mhz beacons also transmit a 121.5mhz homing signal. Thus enabling all SAR a/c to home on the 121.5 signal. I understand all/most USCG SAR a/c can home on 406mhz and trial gave a vastly improved range compared to 121.5. I assume (dangerously) that the incoming SAR-H a/c will also be able to home on 406mhz.
Somewhere I have read about GPS encoded beacons being able to transmit their L+L to SAR units directly on 406mhz. But cant remember the details. Will dig out and post.
2. As stated above the inbuilt 121.5 signal continues to be fitted to 406mhz beacons. So yes SAR units will continue to have this facility.
Ali - Not entirely sure what you mean... But I take it your worried about the 406mhz beacon being detected in the first place. COSPAS/SARSAT will now ONLY detect 406mhz signals, which will be relayed to the appropriate MCC for that Search and Rescue Region. If no reliable authority in the area of the alert then chances are the state registering the beacon will investigate, or pass the alert to a responsible neigbouring SAR authority.
If you meant homing on the 406mhz beacon, then hopefully my 1st two answers will shed some light on the matter.
Cheers
EWD