My Stag sculpture (Oak with Yew Antlers) has now weathered down a fair bit since this pic.

I need to mount it solidly outdoors as it's been accepted by the Gibberd Garden.
I'm thinking of drilling up inside each leg about 100mm and inserting 6mm threaded Stainless Steel rod. The protruding rods could be formed into a loops, and concreted into post holes with concrete (quick drying post set).
1. Does this sound reasonable?
2. How deep should I go with the post holes and the protruding rod?
3. Is 100 mm into each leg enough?
4.Will one of the general purpose building adhesives (you know the sort of Can't believe its not Nails sort of stuff) do the job? (The 2 part epoxies are expensive for a big job.)
5. Should I put some sort of washer (maybe rubber?) or a sacrificial piece of oak under each foot to help protect against rot?
It will doubtless have to withstand being 'ridden' by toddlers
...(I've tested it myself
)
The best answers will receive 25% of my fee.
Del (Oh...forgot to say I'm donating it for free
)