Those sausages look fantastic,
I shot a old old roe buck a few weeks ago, he had one wobbly stub of a tooth left and as expected despite hanging he is as tough as an old boot.
I've literally just finsished making burgers out of one of the haunches. Basic recipe which seems to work for me is 5 parts (by volume) venison, 1 part pork fat (from the butchers), 1 part rusk, as much onion as I deem to be about right, salt and pepper to taste and a little water till the right consistancy is reached.
I used harryMac's seasoning for the first few, they are very nice.
The other half I just used salt, pepper and a little mustard. Tomato Ketchup works really well too, lots of pro'#s use it.