Copper Underwing Pupation Questions

[Me Here]

I'm not really in the habit of carting caterpillars home to raise, but early this year we found a Elephant Hawk pupa and brought it home (due to a unfortunate location) and it went really well.

So I have been actively looking for other hawk or emperor cats to bring home to raise. On a moth walk a few days ago I found a fairly large cat with a slight tail piece, climbing a fence on the road side. I brought him home and ID'ed him as a Copper Underwing. I couldn't get him to eat anything and was ready to take him back into the wild to allow him to pupate (since we couldn't find any information about what it needed) but the next morning he had spun a web around himself under the then wilted leaves of oak and hawthorn, with a few bits of dirt also attached.
Because hes spun this attached to the box and the stuff in the box I feel its best for him to be left there. Its been a few days now, three I think and he still looks quite green in there. So my questions are these:

How long approx. does it take for him to develop the pupa?

The leaves and the bits of dirt are very dry now after three days, does he need to be supplemented with any moisture or fresh leaves for moisture?

Would this species normally prefer to have been under dirt, or is 'leaf litter' where he should be so that I can move him accordingly when hes done?

Thanks for any help, I've been looking everywhere for info and found none so far.
Crystal