Abandoned games - I did a full list in my 2006 Manchester City The Complete Record. The full details are in there, but here's the year and the game:
1895 - Burslem Port Vale (H)
1895 - Burslem Port Vale (A)
1898 - Grimsby (A)
1901 - Stoke (A)
1902 - Preston (A)
1902 - Barnsley (H)
1903 - Small Heath (H)
1913 - Sunderland (H)
1921 - Everton (H)
1936 - Brentford (H)
1956 - Blackpool (H)
1958 - Birmingham (H)
1960 - MUFC (H)
1961 - Luton (A)
1962 - Aston Villa (A)
1965 - Norwich (H)
1969 - Newcastle (H)
1974 - MUFC (A) - though the result was allowed to stand!
1994 - Ipswich (H)
2000 - Ipswich (H)
Hope this helps. As for postponed games, nowhere do we have a definitive list, so I'd be particularly interested if people can add to that. Don't forget though that most times City or their planned League opponents have progressed to 5th round of FA Cup (rules varied, so not every time) then the League game would be postponed. Maybe we should stick with a list of weather (or other unforeseen issues) caused a postponement?