You can combine multiple regular expressions using the Boolean search REGEX operator, e.g.
REGEX "reg.*ex1" OR REGEX "reg.*ex2" OR REGEX "reg.*ex3"
Alternatively if you specify Boolean RegEx for your search type the REGEX operator is implied for each term. If the expression is to be evaluated on a Line by Line basis you can change this option in the Options Tab.
To load criteria from a file use the File List functionality. For example if you created a text file
MyRegex.txt with the three lines:
Then ran the search as:
File name: *.log
Containing Text: =C:\MyRegex.txt
Look In: C:\Log\Folder
It would be the equivalent of the first search. See this QA article for more information:
QA: How can I search a list of keywords inside files?