You are making great progress.
First of all good work seeing off those contractors, they have a phone glued to their ear most of the day so little excuse for the no contact.
I'm really jealous of your blade by the way. It may have set you back a bit but you have an ideal tool there, especially once you have your stump holes to level, it will allow you to make little 'pot-bumps' to allow for the soft stuff to settle, probably with more ease than your excavator unless it has a tilt bucket.
Regarding culverts, what plans do you have there? I can see the logic of waiting and then putting them in later, but if there's naturally a bend or contour where it should go then that's your place. Have seen some around here that have a 'pool' of what we term reject gravel ie large river run with all the fines removed. People put it in at the head of the culvert and often some at the outlet, the idea being that the inlet side won't grow weeds and block up, and the outlet won't erode.. just an idle thought.
If you are pushed for room for your watercourse, remember it can be made quite narrow and maintained with herbicide

won't look as neat as mowed verges but could save you quite a lot of $$$
Good to see a man with a plan, and love the pictures, looks like a great place to be!
Pete