wyn means "white, fair, blessed" in Welsh, yes; it's the male form, the feminine form being
wen.
win also means "friend" in Old English, and
wyn can be a variant of that. There's also
wynn, Germanic for "joy" (see
Rowena).
Ella is short for
Eleanor or
Ellen, but it's also short for any Germanic name containing the element
ali, which means "other" (which is usually intended to mean "foreign" or "stranger", i.e. "anybody
other than us").
So, in short, depending on the elements used and their translations, Ellawyn could mean:
1. "White stranger", "fair stranger", "white foreigner", or "fair foreigner"
2. "Blessed stranger" or "blessed foreigner"
4. "Foreign friend" ("stranger" doesn't sound quite right in this meaning)
5. "Joyful stranger" (or, less literally perhaps, "stranger who brings joy")
Miranda