The "squiggle thing" is originally a short line on the "n", written instead of "nn", the form that should be pronounced like "nh" in portuguese or "gn" in italian, derived from latin (this looooooooots of years ago)
Other curiosities are a line above the "u" in German, when in handwriting it was difficult to tell it from the "n" (an example in Sutterlin fonts.
Another: The "ü" in German is actually an "u" with an "e" above (look again at the "e" in Sutterlin for an example) , instead of "ue", also w a different pronunciation (same for "ö").
And in "Mexico" or "Texas" the original "x" is not "ks" but the spanish "j", a sound that i believe doesn't exist in English (stronger than "h")
Well observed :-) But I think that the Spaniards are just more generous with their wishes (plural) The "argies" wish you only a good "today".
But BTW buenos dias refers actually to the morning (good morning), after noon it is for example buenas tardes (always plural).
And by the way again you don't ever say "good morningS (or afternoonS)" as far as I know.