1. Does it affect party members
2. How does it interact with Spell Resistance
3. Is it a save every round?
1) Yes. Warn your party members to not look at you and they'll be fine.
2) It is subject to spell resistence and you use the caster level of the item (11) when you make a check to overcome spell resistence.
3) If they fail a check, they are dazed for 1d4+1 rounds and get no additional saves. Every time they look at the robe thereafter would require another save (although anything with an intelligent score is unlikely to do so after getting hit with it).