worktop radius

[jonny round boy]

In terms of size of studding, I'd say 10mm. Just because you'll have a 1/2" cutter in the router already - rout a slot roughly 12-15mm deep, and then glue the studding in with something like this, but TBH I've never actually done this myself (it just seems like a good idea!) so I'd try it on an offcut first to make sure there's no reaction between the resin & the timber.

Yes, do all the cutting, glueing & routing first. Then oil the undersides. Then fit the tops, and oil the top faces.