It looks oblong because only a portion of the Moon facing the Earth is being lit up. The lower left portion in your photo is in shadow.
You can get images from stills. You can even get good images from single stills. The two main pieces of advice I can offer are learn about sharpening. And learn about histogram stretching.
For stacking, try, Planetary System Stacker, Autostakkert, or Registax. All of these are free. All of these understand the moon. Registax is no longer maintained. Both of the others are. There is a support thread for Planetary System Stacker here on cloudy nights. The developer is active in the forums.
A lot of people swear by the wavelet sharpening in RegiStax.
There isn't a normally accepted way. Do what you like and have the equipment and expertise to support.
However some of the best lunar images in the forums use equatorial mounts, telescopes, and dedicated planetary cameras. They use the planetary cameras to collect 1000s of images which they then stack.
There are books specifically on lunar imaging.
I would suggest avoiding this one:
The Moon: A Beginner’s Guide to Lunar Features and Photography by James Harrop
The images in the book are oversharpened and in some cases show terrible CA.
It does, however, go over the basics of equipment choice and related concepts.
This book is better:
Shoot the Moon (A Complete Guide to Lunar Imaging) by Nicolas Dupont-Bloch
To me this book seems disorganized. However it has a lot of info in it about equipment, technique, and concepts. I believe the author is in the forum.
If you get one of these I would definitely suggest Shoot the Moon over The Moon.
Another approach will be to try to take pictures and post here with questions. I find specific questions will get good replies.
A basic workflow.
Set up your camera on an equatorial mount. (Just skip the whole thing with Field Rotation. There are no applications that I know of that deal with Field Rotation. Autostakkert claims to, but my attempts at using it did not go well. The only alternative is to write your own code to derotate.)
If your camera/lens support it, autofocus and lock the focus. Otherwise use focus peaking and magnified view to get best focus.
Set the exposure so that the histogram goes to 75%. (This leaves headroom later for sharpening.) Don't be afraid to use ISO. Do keep shutter speed faster then 1/60 or 1/120th of a second. If it is a normal camera lens, maybe stop down the aperture to get to the best performance of the lens. Read about your lens or do some test shots to determine best/sharpest aperture.
Take some number of shots. If your ISO is high, take more shots. If the seeing is lousy, take more shots or enjoy an evening of visual.
Avoid the temptation to use an ordinary DSLR or MILC as a film camera unless you can get one with RAW 1 to 1 pixel recording. (Actually do this if you want to, just recognize that movie modes in cameras take short cuts to get the image in the file. They tend to use lossy compression, they tend to skip lines or bin pixels.YMMV)
Preprocess your shots with PIPP. Let PIPP crop your shots. PIPP has lots of other features. For your camera it may make sense to use some of them.
Load up the PIPP processed shots in Planetary System Stacker or Autostakkert.
Take single frame output and color correct, histogram stretch and sharpen. (Sharpen last.)
Post to Cloudy Nights and ask for advice.
