"2. For the privacy berm, would 15ft be enough space from the pond edge and where the incline of the berm begins? I'm hoping that will allow for enough space to walk/drive around the pond but also be enough distance to not have a bunch of silt get washed back into the pond until we get some vegetation on it."
Yes, 15 feet should be fine for a driving path around the pond.
If you are worried about the silt, I would grade a reverse slope from the edge of the pond to the start of the berm. (The pond edge is higher.)
You could also have a slight reverse slope on the top of the berm, so a heavy rainfall would flow away from the pond and most of the erosion would be on the backside of the berm.
"3. Does 2 days sound reasonable to build a .25 pond that deep with an excavator and dozer running?"
2 days sounds reasonable to me with a 336 excavator and an appropriately sized dozer. (I am not an expert!) UNLESS you hit a lot of wet, sloppy material. Wet sand will not come out in heaped buckets and cannot be spread with the dozer. This problem could double your time (or worse). The excavator can do wet clay, but the dozer will also have trouble with that material.
I have some similar ponds planned for my farm. I am getting some more soil samples from the NRCS drilling rig to finalize my plans.
I would highly recommend that you get some soil samples BEFORE moving in the heavy equipment. Ideally, you want to get a few feet deeper than your projected 15 foot max. depth.
I would also plan the project for the driest time of the year to avoid groundwater as much as possible.
