For 1, after a look over the Internet, it seems without fada is more common.
The following site shows some older forms of the name:
http://medievalscotland.org/kmo/AnnalsI ... raid.shtmlThe headword has fada but few of the entries do, possibly because of usage in the older language.
1, 2, and 3 are pronounced differently with some variations between dialects (these explanations are all approximations):
1. Without fada, the first syllable SHOULD sound like "sha" in "shack" (although it could be pronounced as if it had fada >; with fada, like "shay" as in "shake" or "she-" in "shelf" or somewhere in between.
"-fraidh" sounds close to "fray" or "fri" as in "fridge" with a light "g" at the end. Sometimes you can't even hear the final "g".
2. "sio-" can be either "shoo-" as in "shook" or like "shoe" (Conamara).
3. "shay" (as in "shake") and "fra" as in "frolick".
Listen: https://forvo.com/word/s%C3%A9afra/#gaWait for more input. Maybe someone else here (Bríd) can do some sound files for you. I have no idea how to do this.
Good luck!