1) The word ‘brest’ could mean ‘damaged’ so perhaps this was a reference to ‘mould’, that is good land, which was deemed to be ‘spoilt’ because it lay uncultivated.
I have found no explanation of this word in the OED or in specialist glossaries but it occurs in one or two fourteenth-century court rolls for the manor of Wakefield: 1327 ‘land lying unoccupied at Horbury called Molebrist’
1338 ‘6d. for leave to take an acre lying molbrist on the lord’, Hipperholme
1340 ‘eight acres in Holne … lies moldbrest for lack of tenants’, Holme. These occur in translated passages but in each case the clerk used the regional term in the Latin text. In the notes of the Yorkshire antiquary Roger Dodsworth is a passage from the same court rolls which relates to land in Ossett. The extract is dated 1346 but will have been translated by him in the first half of the seventeenth century: The jurors say ... that the custome is here that although any land lye fresh and unmanured whilest distresse can be found in herbage or meadow belonging to the same that the sayd land shall not be accompted for Moldebrest yet they say that there was there neither Herbage nor meadow where a distresse for the Lord’s farme might be made. And so the sayd Land lay moldbrest three yeares.