Rule number 1: NEVER trust a HD Dealer to do what they say they will do, or have done. In 4 weeks, the oil would not get milky unless you went out and started it every day for 5 minutes, and even then I don't think so...
I'm not saying that all HD Dealers are bad, but there are a good number of them that I wouldn't trust to change a spark plug, or anything else. Since you obviously have some wrenching ability, just find you a shop manual for your bike and do it all yourself...at least you can only blame yourself then

Or, if you don't want to fool with it, talk around to other HD owners in your area and find a good independent shop...there are plenty that would love to work on that bike.
As far as the plugs? The stock ones work just fine, but since you have already bought the "SE" plugs, use 'em. I'm not sure about the gap, but 38 doesn't sound unreasonable.
It takes a good 20-30 minutes of riding to get everything up to proper operating temps so that any condensation in the oil will boil off. You're better off just not riding instead of cranking the bike and letting it idle, even for long periods of time...which is not good for an air cooled engine anyway.