99 Ford windstar brakes

i have brake fluid leaking from the master cylinder going into the booster right were they meet i took the brake cylinder off but i could not seen anything that looked broken there is a gasket right inside the booster it looks fine not broken what do i need to do or does the parts need to be replaced

Fluid leaking where the master cylinder meets the booster is generally an indication that the O-rings inside the master cylinder have failed. You probably won't be able to see anything wrong once the master cylinder is removed - the O-rings are up inside.

I'd replace the master cylinder. Get a master cylinder "bench bleed kit", which is a collection of plastic fittings that will make it easy for you to get rid of all air bubbles in the master cylinder before installing it (the last one I bought was $10-$15, and well worth it).

If you haven't done so already, make sure you have the new style of brake pressure sensor (the sensor threaded into the bottom of the master cylinder, toward the front of the cylinder as mounted in the van). It has a two-pin electrical connector going to it. The original design is noted for failing (see wiswind's "sticky" posts at the top of this forum for more info - http://www.automotiveforums.com/vbulletin/showthread.php?t=681061).

I can't address your concerns about the booster unit. I'm not sure if some fluid in the unit will cause a problem or not...