Re Wallace being of Welsh ancestry. Southern Scotland was at one time a British kingdom, Welsh was the language spoken in Strathclyde as the placenames show.
The surname Wallace is from the same root as the word 'Welsh'. Basically, it means ' a foreigner' or 'a stranger', and it crops up, with variations, all over Europe.
This is what the Oxford English Dictionary says: Cognate with Old Frisian
walsk ‘French’ (rare), Old High German
walesg ,
walisc ,
walahisc ‘Latin’, ‘Romance’ (Middle High German
walhisch ,
welhisch ,
walsch ,
welsch ‘Italian’, ‘French’, ‘Romance’; German
welsch , in the same senses), Middle Dutch
walsc ‘French’, ‘Italian’, ‘Walloon’, ‘speaking a Romance language, especially French’ (Dutch
waalsch ‘Walloon’, ‘speaking a Romance language, especially French’), Middle Low German
Walsch ,
Wallesch ‘Romance, especially Italian’, Old Icelandic
valskr ‘foreign, especially French’, Old Swedish
valsker ‘French’, ‘Italian’, ‘from a southern country’, ‘foreign’ (Swedish
välsk ), Danish
vælsk ‘from a Romance-speaking country, especially Italian or (sometimes) French’, (also) ‘Welsh’ < the Germanic base of Old English
Wealh ,
Walh (see note below) + Germanic base of -ish suffix1. Compare post-classical Latin
Waliscus ,
Walliscus (1086 in Domesday Book; c1114 in a Latin version of the early Old English Laws of Ine: compare quot. eOE at Welshman n. 1aα. ), Anglo-Norman
Waleis ,
Walais ,
Gualeis ,
Galays , etc., Old French
galeis ,
galeis , (northern)
walois ,
walesche (French gallois ) (adjective) ‘Welsh’ (c1170), (noun) ‘Welsh person’, ‘the Welsh language’ (both 1155), ‘the French language’ (c1283, only in Old French and Middle French in areas bordering Germanic speaking territories). Compare also post-classical Latin
Wallensis ,
Gualensis ,
Galensis (from 1086 in British sources),
Valicus ,
Wallicus (from 1252 in British sources), both adjectives in sense ‘Welsh’,
Wallus ,
Guallus (adjective) ‘Welsh’, (noun) ‘Welshman’ (from a1142 in British sources), etc.
So even Gaul and Gallic, and de Gaulle, are from the same root. And I believe that the surname Guelph or Welf is also connected.
So while it is true that the surname 'Wallace' basically means 'Welsh', it isn't evidence that he is actually a descendant of someone who came fromwhat we would now call Wales. The word would be used by the Anglian population of Lothian and Northumbria to describe a speaker of the British language from the south-west of Scotland.
PS the modern German-speaking wine industry uses a type of grape they call 'Welschriesling', indicating that it is a 'foreign' stock.