leaking coolant, burning oil smell, clunking engine won't start.
hmmmm.
check the coolant level/color. check the oil level/color.
crack the oil drain plug and see what comes out.
I'm thinking this might be your head gasket. (and subsequent failures)
Verify where the coolant is leaking from.
hope i'm wrong.
to expand on subsequent failures:
a leaking head gasket could cause the oil burning smell from leaking onto your exhaust(which could be mistake for valve cover)
leaking hg would cause a coolant leak(which could be mistaken for valve cover)
hg failure would cause all sorts of fluid mixing and therefore water pump failure and then tb failure and so on.
failed hg could fill your cylinders with coolant and cause it to not start.
these issues could certainly lead to a spun bearing (read clunk)
again; for your sake I hope that's not the case.