Well there goes the neighbourhood! To keep to the subject, there are 3 independent attitude references (references , not necessarily indicators). Each of the pilots has his own independent Primary Flight Display CRT and Navigation display CRT. The Primary Flight Display can be switched over to the former Navigation display in the event of failure of the screen. Any of the three attitude references can be switched to the Primary Flight Display for attitude information. This gives so much redundancy that a traditional back up standby third attitude display is really not needed or necessary (though supplied to keep people happy).
As to partial panel training, it's not required. Most pilots have done it on other types early in their careers- enough I would think. I don't believe big jets present any additional problems over smaller types.
These are the opinions of Notso. No doubt having been through with a toothcomb, a bore like 411A will jump to disagree with it somewhere. Sad sad man!