cognate vocab as a measure of relatedness

[Adrian Clynes]

I would be grateful for a quick answer or answers to one or more of the
following:
1) What percentage of basic vocabulary is cognate in English and German,
using (say) a 200-item Swadesh list?
2) Ditto, for English and French?
3) Is there a commonly accepted percentage of cognate basic vocabulary, at
or below which one might expect two varieties to be considered distinct
languages, rather than dialects of the same language?
4) Can you recommend a reference discussing this kind of approach?
Thanks,
Adrian Clynes