Looking quickly through your list, you seem to have most things covered. Your letter of support as UK sponsor should be no longer than two sides of A4, in which you give an outline of relationship from first contact, first and subsequent meetings, deepening relationship, engagement and hope and plan for the future: to marry and settle in UK. Your fiancé should do the same, called a letter of introduction. The two versions should broadly agree, but without copying from each other.
Any savings?
In addition to his CV, to show his job prospect, enclose details of a UK job vacancy he may be qualified to apply for, with salary offered.