Hi David,
See if these works:
1)
=IF(A2="","",IF(COUNTIFS(A:A,A2,B:B,"vacation"),"Yes Vacation or Sickness Recorded","Only Work Recorded - No Vacation Recorded"))
2)
=IF(B2="Work","",SUM(SUMIFS(C:C,A:A,A2,B:B,{"vacation","Sickness"})))
3)
=EDATE(D2,12-MONTH(D2))-D2
Regards,