You will not be able to see anything on the moon during the partial phases of the eclipse! The dynamic range necessary is way beyond that of any DSLR.
Check my album at
Transit of Venus for some pictures of the sun.
For those pictures, I used a 10-stop ND filter along with both 1.4x and 2x teleconverters. The net effect is at least 13 stops of attenuation compared with my 300mm telephoto lens by itself.
These exposures used f11 and 1/2500 seconds, at ISO 100.
To compare to an exposure of the full moon, one could use the “sunny 16" rule (the full moon is basically in full sunshine, just like high noon here at home), although the surface of the moon is rather darker (a stop or two) than the earth. Thus, you might try ISO 100, f16, and 1/100 second exposure.
This is at least 16 stops down from the sun (13 for the TCs and filter, -1 for f11 versus f16, and 4+ for 1/2500 versus 1/100 sec). And, that is for full moon. During the eclipse, we are looking at the DARK side of the moon, and that is really dark, although a bit of earthshine lightens it up. I’d say allow another 4 or 5 stops at least.
So, the side of moon that we can see will be some 20 stops or more darker than the sun during the partial phase. That is a factor of a million!! (2 to the twentieth power)
No camera any of us owns has anywhere near that dynamic range. So, all you will see of the moon until, perhaps totality (check out that Astro pic of the day referred to above, for the earthshine result), is a silhouette!!!!!!!!!!!!!!!!!!!!!
As to the focal length you want for the eclipse, here is a full-frame (significantly reduced in quality - all I want to show is the size of the solar image) image from my Venus transit series referenced above. This is for my Pentax 300mm with both a 1.4x and 2x TC, or about a 900mm equivalent focal length lens, mounted an a K5D (i.e. APS-C) camera. If you want a nearly full-frame image of the sun, you need a long lens (or some TCs)! If this was on a K1, the image of the sun would be 1.5 times smaller in the full frame.
Only at totality do you want/need a wider field view, to get the corona. In that case, you will want a wide range of exposures, again as noted above, with reference to the Astro pic of the day.