Not quite sure which bit requires further explanation. The primitive crossbow will be explained further when I get round to building it!
It will have a wooden bow (prod) held onto the stock with a binding similar to the repro' mediaeval bow on my website. The trigger mecanism will be a groove across the stock which the string pulls back and drops into. A wooden peg will press up through the stock to push the string up out of the groove, the peg being pressed up by a long wooden trigger beneath the stock
The apple scratter was inspired by this link http://www.sentex.net/~mwandel/press/apple_grinder.html and there is tons of stuff on Youtube about building apple scratters (grinders) and presses.
To cover more about gathering apparently rotten Oak, I went back and took a couple of pics from where I'd cut it. You can see from the Ivy growth and rot that it has been down for a fair time. The fresh cut face has now started to split as it has had a week to dry out, but you can see the heart wood is sound.