For large-aperture ground-based telescopes operating in the visible spectrum, the seeing limit is the dominant effect. Atmospheric turbulence is a bigger factor than the precision of your optics, in other words. See https://en.m.wikipedia.org/wiki/Astronomical_seeing
(Space telescopes are diffraction-limited but have other constraints, like mass budget and cost, that keep them from being as large as ground based facilities.)
Assuming you mean FITS when you refer to the weird file format, you may be interested in this (well-maintained, mature) Python wrapper library: http://docs.astropy.org/en/stable/io/fits/
FITS does a lot of stuff that PNG and friends can't, so it remains in use to this day.
I was using Evernote (and resenting it) until they gave me a reason to switch... so far, still haven't found the perfect solution. I've tried Quiver for Mac (http://happenapps.com/#quiver) and MS OneNote for Mac and iOS (though obviously more platforms are supported) (http://www.onenote.com).
Quiver is pretty good, but the 'cells' metaphor ended up being less useful than I thought it would be. Didn't really impede me at all compared to Evernote, though, since it's not something Evernote had. Quiver also lacks an iOS app that can author/edit notes. The beta version can read notes.
OneNote has the disadvantage of being an MS product... I was able to import my Evernote notes, but the importer is Windows-only so I had to borrow a Windows PC. Once the notes were in, I looked for a way to export them, and it appears that that was a one-way trip. Yikes.
The iOS app for OneNote is pretty good, though. All the major features are there.
I'm using OneNote for now, but still looking (and working on my own replacement app in my copious free time).
Not really my department! I do work at STScI, which operates the MAST archive that will eventually hold all this data, so I'm sure someone in my building knows.
I'm working on WebbPSF, a tool to simulate PSFs for the Webb instruments. I'm also adapting it for WFIRST, a future mission. It's going to be kind of like TinyTim is for Hubble when it's done.
This video shows the steps that take it from a folded-up thing stuffed into a rocket to a deployed telescope at L2: https://www.youtube.com/watch?v=bTxLAGchWnA The rocket is out of the picture fairly early on in the timeline.
(Space telescopes are diffraction-limited but have other constraints, like mass budget and cost, that keep them from being as large as ground based facilities.)