I've tried wildcard'ing the search string but cannot get it to work - I always seem to end up greedily taking up a lot of the rest of the file

Wildcards are greedy by default, which means that they'll take as much as they can, as you have already seen. Try appending a question mark to the quantifier, to make it non-greedy, ie use abc.*? instead of abc.*.

Also - I cannot get my search to find these "search strings" that are split over a line - I guess if I can get the wildcard working I could put a linefeed in there ?

Use the /s modifier in the regex.