Hi Ken,
Burial records will not show that I am afraid, (age and residence) nor will the death certificate. Death cert will show age and residence along with the informant which may help but that is all.
Personally, I am pretty confident he was deceased by 1841. Widow would not be referring to the first husband, that would not make sense. I feel she was widowed by 1841, possibly a lot sooner due to the lack of further children married 1821 three births 1822, 1824 and 1826 and then nothing. Yes she may have left Padstow and had more elsewhere after this but none showing on the census sort of makes me feel he had been dead for some time.
That line in the census is for occupation not marital status. We see this quite often in the census. Widow or Wife was entered but later crossed out as it was not an occupation but rather a marital status and did not belong there. (It is handy though that it was originally included) I do believe she was already widowed by then. Being a sailor of course he may have died anywhere I am afraid. I did not find burials in Padstow for either of her husbands.
As to the 1847 death. Unfortunately age was not included in the index at this time so you would need either the burial record or the death cert to get that. In 1841 we have 4 Francis Websters. Aged 25 in Bodmin, aged 10 in Crowan, and aged 6 and 8 in Illogan. In 1851 3 can be accounted for. The 10 year old son of Elizabeth from Crowan is missing. Crowan is in the Helston district
Likewise in the baptism entry I think the person entering the details probably the clerk made an error and crossed it out. Given the entries we have for him I do not think his name was William. With the baptism for Henry so much was crossed out and redone.
Cheers Kris