The SpaceX recoverable first stage - how much does the landing legs and guidance gear add to the weight and what percentage of empty weight.?

Well it is a considerable weight.

Not to mention the fuel that is carried to slow it down for a soft landing.

That is weight that had to be lifted at lift-off -- and it could have been used to get the rocket to a higher orbit.

And it is not just the legs, and the mechanism to deploy them and lock them in place.

The savings in re-using the first stage also have to off-set against the cost of refurbishing after each flight. Which includes having a barge out in the Atlantic Ocean.

The lessons learned from the Space Shuttle is that --

a) the cost of refurbishment can exceed the cost of building a brand new rocket.

b) raises the risk of a catastrophic failure.

Landing upright is a stupid idea. A good parachute system and a carefully planned launch will allow it to touch down on land by parachute, saving leg weight, guidance system and landing fuel which allows more weight to be launched