Difficult to tell about the seal, as you say, could be a magnifying effect caused by a build up of oil - but it's not a terribly expensive part and replacing it is a no brainer.
The missing bit on the yoke seems odd - can't see how this would occur in use, can't see it's been ground for clearance on the grease nipple. IMO it shouldn't be like that and, though not a cheap job, needing the attention of a propshaft specialist (yoke replacement, UJ replacement , front and rear I guess, whilst you're at it , and a balance.
A good £100 I expect.
Allen