The taper pattern is not critical. The important part is not to have a sharp change in diameter. That is where a splice will break. I like the 3-4 pattern. It is easier to bury.
A fid is a splicing tool. They are usually tubular/round and made of aluminium. They have measurements on them that depend on rope diameter. A 1/2 inch fid is 21X the rope diameter. A short fid is shorter than a long fid. A long fid is shorter than a fid.
A fid is not necessary but it makes...