Good one Geo, and coincidentally, I've just been messing about with the same old kit, and have built a few before. I decided to engrave the panel lines and, surprisingly, this didn't take very long at all, just following the raised lines, and then slicing off the detritus.
I'm surprised at the one-piece canopy though, as my kit, and all those before, have a rather nice, clear, two-part canopy. The detail looks quite basic now, but back when the kit was first released, and even in the late 1980's, it was considered to be good.
Diameter for the hypo tubes would be somewhere in the region of 1mm, maybe 1.25mm - basically, if they look right, they are right! The P-47 barrel jackets, as you probably know, where smooth, fairly heavy-weight items, so a bit larger in diameter than the perforated version. I'll probably just stick with the kit parts, as the model will be part of a small diorama, and hopefully they won't be too noticeable.