http://www.mnrepeaters.org/MN_List.pdf - from the Minnesota repeater council, so probably the most authoritative. Also it is sorted by regions, which is helpful.
Well finding younger hams in general is rather difficult since our hobby seems to be populated by older people. However I'm a younger ham in the twin cities area, i usually am on the 146.85 repeater. As far as up in the st cloud area, my best suggestion would be to look at the MN repeater council page.