If I use a microjig I just set the depth 2-4 feet from the strike indicator? I try different depths to find the Crappie? What I have heard is you have to be at the depth they are at...

Sounds like white, yellow, and Chartreuse are the colors to use? I looked at the Crappy Candy lure on FlyAnglers (http://www.flyanglersonline.com/flytying/fotw2/052801fotw.php)
and they made it seem quite simple. You use a weighted jig and put it in the right place and it sinks. That way you will find them at the proper depth if they are there.

So perhaps I will try to target Crappie this weekend, as May is spawning time for Crappie, right?

Feb through April is crappie spawning time in this part of the state. The crappie are moving back to their deep water structure now. Minnows and jigs are what works best until next spring...

If I weere to be able to go flyfishing for crappie I'd still work the weedy or stumpy shorelines with a strike indicator over a microjig. Once you find them cast at nearby stumps, standing trees or even lone twigs. Still hearing reports of fat females.
Hook,Line aand Sinker is right. They should be nudging back toward 6-15 ft. Cast over and around any brushpiles you know of.
As far as depth under your indicator. It's kinda determined by the depth you're fishing and the depth you can accurately cast a micro jig and bobber rig. The fish are still gonna relate to wood and bottom, so keep close to both.