WRT - The availability rate and maintenance vs flight hours of the F-14, these were comparable with other 3.5 gen aircraft.
To the best of my knowledge their availability during their final cruises was much improved simply because the competition for spare parts was so low they had buckets full of spares allowing most problems to be solved by pulling assemblies / black boxes and replacing them.
During their more active service with multiple squadrons per ship performing high tempo operations post 2001, contention over spare parts was much higher and there simply was not the reserves of parts as the aircraft were already known to be due for retirement (planned) 2008 - the DOD was not going to order up vast reserves of parts when the maintenance crews at squadron level could pull and fix many of the parts rather than replace them.
Further - in this example of a 'modernised' jet the vast majority of issues would be solved with newer more reliable electronics coupled with a reduction in hydraulic components.
An AESA antenna for the AWG-9 / APG-71 would much like the APG-63 v3 F-15s have eliminated bleeding noses. A new FBW control system with electric actuation would eliminate many more potential issues with control surfaces.
In short - the airframe of the F-14 on paper is completely sound and even sticking with engines in the F110 power class, new build jets with completely modernised internal components coupled with a supply chain would have much much better availability rates and flight / maintenance ratio than the real F-14 A-D models did.
The reality is all the real jets were old, rebuilds of older jets, and all of the more extensive new build F-14 designs from the Quickstrike to the AT21 were not built.
When tax dollars on this scale are being waved around there will always be a tension between improved internals for a known design being relatively low risk vs new designs with the potential to be all of this with improved performance and more.