1998 Honda foreman 450es stuck in reverse
 

Manual shift will not work either, having problems grasping and pulling front drive shaft out even after removing the three bolts, and top mount on the differential, flying blind as this is my first atv to tackle.

You don't need the shaft out to get at the selectors, just the clutch cover, but if you really want it out of the way, shove the front diff as far forward as it will go, so the front mounting is above the crossmember it was bolted to. Then shove the prop shaft forwards at the muff coupling next to the engine, it is spring loaded and needs a good shove, if splines are worn it may catch on them, but it should shove just far enough to pop out of the engine splines. Then it can be moved sideways to clear the engine splines and pulled out of the diff. The problem with the selectors is usually the lever or pawl which moves the star wheel round, or the star wheel loose on the shift drum, but I have known gears inside the reduction box behind the shift motor to break, so check these before delving into the clutch housing.