i\'ve been trying for some time now to get this working, but i can\'t find a solution to this task myself - ok, i\'m very new to regex-use but quite interested to learn, hop
You can use a regex like this:
\(.*?\)|(\w+)
Working demo
Then on your Find/Replace dialog you can put \U\1 on Replace with. So, if you go over Find Next you can replace the string to generate the uppercase output.

You can use this regex:
(.+?)\[
Working demo

For part 1 you can use
Find: ^(.*?)(?=\()
Replace \U\1
Make sure regex is selected
for part 2
Find: ^(.*?)(\(.*?\))
Replace:%htmltag%\1%/htmltag%\2
which takes
WORD1 WORD2 WORD3 (some words in brackets)
WORD1 (some words in brackets)
WORD1, WORD2 (some words in brackets)
and converts it to
%htmltag%WORD1 WORD2 WORD3 %/htmltag%(some words in brackets)
%htmltag%WORD1 %/htmltag%(some words in brackets)
%htmltag%WORD1, WORD2 %/htmltag%(some words in brackets)