DOUGLAS: Two Questions

Coats of arms used by the Douglas (L) and Moray-
Murray Clans. Both are descended from a Flemish 
settler, Freskin, and both use three five-pointed 
silver (argent) stars on a blue (azure) field.

My quest for origins of the stars in the American Stars and Stripes led me to the Douglas and Murray families (clans) of Scotland. 

Their shields of white (argent) stars on a blue (azure) background are the closest approximation to the white stars on a blue field in the canton of the Stars and Stripes.

George Washington's ancestor William de Hertburn in 1183 acquired the Wessyngton/Washington property in Durham County, near the Scottish border. He was of Scottish ancestry. The Washingtons moved to Sulgrave Manor in Northamptonshire much later, in 1539.

My theory has been that the Washington arms were modeled on the Douglas arms with the tincture changed from blue (azure) to red (gules), as the Washington estate was on the British (red cross of St. George) side of the border.

Arms showing St Andrews saltire (white X on blue
field) and St George cross (red + on white field).

My two questions are:

1. Is the blue field in the canton of the Stars and Stripes derived from the blue field of the St. Andrew's saltire via the Douglas arms? 

2. What might have inspired the five-pointed stars in the Douglas arms?

Related posts:

The Douglas Arms in France . Oxford Stars