Yes, 1) is possible with a regular expression.
However, you need to specify more precisely what you mean by 'other than a number' and exactly where you want it.
For example do you want to replace in the field TITLE
"This is : colon"
becomes
"This is . colon"
Please show us some real examples.
For 2: This would only be possible if you define what you mean by 'or any similar key designation'. A regular expression cannot 'guess' what you mean. You need to define exactly for example
" in A Minor" -> delete
" in B Major" -> Delete
" in A Minority " - leave untouched
Please show us some real examples.
For those interested: \D+ means "any character that's not a digit, repeated at least once"
while \d+ means "a digit, repeated at least once"
(\D+): captures one or more non-digit characters followed by a colon.
In the replacement string, $1 refers to the text captured by the first capture group, so $1. replaces each match with the captured text followed by a period.