2) How many Spitfire Mk''s were there?
Spitfire fighter marks that saw wartime service:
Mk I (1,569 produced, Merlin II/III engine)
Mk II (921 produced, Merlin XII engine)
Mk V (6,480 produced, Merlin 45,46,50,55 engine)
Mk VI (100 produced, Merlin 46/47 engine)
Mk VII (140 produced, Merlin 61,64,71 engine)
Mk VIII (1,659 produced, Merlin 61,63,70 engine)
Mk IX (5,948 produced, Merlin 61,63,63A,70 engine)
Mk XII (120 produced, Griffon III/IV engine)
Mk XIV (944 produced, Griffon 61,66,65 engine)
Mk XVI (1050 produced, Packard Merlin 266 engine)
Mk XXI (120 produced, Griffon 65/66 engine)
Dedicated photo recon marks seeing wartime service:
PR X (Mk VII conversion, 16 produced)
PR XI (MK IX conversion, 471 produced)
PR XIX (Mk XIV conversion, 225 produced)
There were also a plethora of other conversions, both unarmed and armed. There were at least five different conversions of Mk Is and then there were the FR (Fighter Reconnaissance) Mk IXs, and FR Mk XIVs, as well as the PR XIII (converted Mk I/II/V airframes with 4 .303s retained, dedicated to low level recon), PR Mk IXs ( standard Mk IX with guns removed and cameras installed).