michael I do similar to you...I sing using cdg as backing and I too rip my discs to my laptop so as I can change course in an instant rather than have to fossick around looking for a disc. It gives me the freedom and the confidence to read a crowd, knowing that I can change my songs and style in an instant to suit.
Really its all trial and error with efx. Pick one you feel sounds good and turn it up just enough that you dont necessarily notice it there, but you do notice when its not.
Remember that ever venue will vary, but if you are playing to oldies then please do remember their hearing aids, those suckers are sensitive and there is nothing worse than a whinging geriatric (I speak from experience)
good luck with your gigs and welcome to KS, hope we hear you sub on SS in the near future also