With 8600 miles, it'll have been standing for a long while and the leaks will occur after 600-1000 miles. Those gaskets will have dried out and tend to hold up for a while when you start riding again and then take you by surprise.
Not to bad a job, replacing head- foot- and oilpan gaskets plus pushrod rubbers plus carb manifolds and diagrams, but just don't be surprised when you need to.
I wouldn't care about the gearbox, change oil (all oils anyway) and start riding the thing, those teeth are just starting to get worn in. Any good dealer will be able to tell you if the recall has been done and if you're still eligible in case it hasn't been done yet.