Sure, that works. Like I said, if they're both happy to come, then go for Austin, definitely: he knows the league, and he's scored at Kane-esque levels in the league before. But risking a bit of disharmony by having Austin (for example) grumbling about being second-fiddle to Kane and thus not getting into the England side that Kane's already in...not sure if that's the best thing to do given the chemistry we presently possess.
We won't spend anything beyond what we make in January, but I agree that we could still get the cover we need without going into the red spending-wise: we might need to shift Townsend, but that doesn't leave us short of cover in the area he's vacating anyway.
I don't think it would cause disharmony. Austin came into the game late I think from non league so I get the impression he would have the mentality of being pleased to have been signed by a top 6 club yet knowing the hard work continues. I personally think he would have to be mad to think he will be selected as it stands for the Euros anyway given his playing for QPR and how well Vardy and Kane have done without taking into account Walcott, Welbeck and Sturbridge, who are all above him In the pecking order.