Billy is correct-- Below is a pic of the shaft, reverse gear and clutch dog out of my Mariner outboard, which are very similar to the Alpha parts. Notice the teeth of the dog that contact the forward gear are "ramped". The teeth within the forward gear are ramped in mirror image. The dog is spring loaded-- when the dog and the gear are connected, the square edges of the teeth make a firm connection. But, if for any reason the prop should turn slower than the shaft, the ramps will let the dog move back on the shaft and "ratchet", which is what's happening when you turn the prop backwards while in gear, that's your clicking noise. Now, if you'll look at my pic, you'll notice the reverse-side of the dog ISN'T ramped, it just has 3 "tabs", which fit into the cavities between the tabs in the reverse gear. In your Alpha, both the forward and reverse gears are ramped, just one of the differences.

As for your hard-to-get-into-reverse problem...The reason I had this thing apart was because the dog shaft-pin was broken in half...

Because the dog is spring-loaded towards the forward gear, going into forward is no problem even with a broken pin. However, the pin is the 'pushing point' of the dog, and when trying to push the dog towards the reverse gear, the broken pin resulted in about 1/8" of slack, and the dog wouldn't move far enough to engage the reverse gear---
HOPEFULLY your problem is just that your cable needs adjusting or tightening. You should be able to get the cable adjusted so it will shift into reverse satisfactorily without it affecting forward and neutral shifting.