Nigel,
Your penultimate question - "the gearbox leaks oil by the bucket into the bellhousing, is this a felt seal?" The answer is, yes it is a felt seal, but the seal only 'controls' the leakage. Any oil that passes the seal, drains down to lubricate the front layshaft bearing. If a sealed bearing has been fitted to the layshaft, it probably stops that oil getting to the bearing - in which case it has no option but to leak into the bellhousing. Also, if the gearbox is stood on it's end (even with the open bearing), the oil will fed back up the oilway to deposit itself on the workshop floor! This is the case with all postwar gearboxes.
Regards,
Eddie.