I find the old Lincoln Wills fascinating but I have difficulty in knowing what the figures for cash sums mean. For example, often quoted is vjs or viijd - is this five shillings or seven pence? I hope you can help.

That's right; 'l' for pounds, 's' for shillings, 'd' for pence.
Also, the last 'i' in a string of numerals is often given as j, so 'viij' is in fact 8.