Hi Isabella,
Probate was left to Alfred COULTHARD means that he was the executor of the Will. He was given authority to handle the assets - pay his bills, collect any money owed to the deceased and then had to dish out the money as directed in the Will. Alfred COULTHARD may have received nothing himself though often he would be allowed expenses and given some money for his trouble.
Often the Executors would be or would include a bank or solicitor though that would cost. Typically a bank will charge several thousand pounds these days.
"Resworn" may just mean they got a better idea of how much the Estate (the assets) were worth though sometimes if an Executor failed to do his job they would swear in another Executor.
"Peruvian House" just means that in addition to his house being number 4 he gave it the name "Peruvian House" as some people called there houses "Dunroamin"
"10s 4d" - oh you are young (or maybe not British). Before decimalisation in 1971ish we had L S D - Pounds Shilling and Pence. 12 pence made one shilling and 20 shillings made one pound. I forget why pence was D and not P.
You should get a copy of the Will to see what it says. Only costs about £6.
Probate records after 1858 can be obtained from here:
http://www.justice.gov.uk/courts/probate/copies-of-grants-wi...Bryan
PS
number 4 Windsor Terrace is still there though it seems they no longer call it "Peruvian House".