Does leg strengthening help with leg lengthening? I've read a mixture of things: I've heard professional athletes who break their legs (like footballers) have a better recover because of their good physical conditioning (but I don't know if their super strong legs are a part of this 'good conditioning'). But I've also read having strong legs makes the legs more rigid and less easy to lengthen - which seems to make sense. Also working out can make your bones bigger (woolf's law) - the analogy of a tree comes to mind - a great old oak will be difficult to mend if it's trunk breaks, but a young tree with a thinner trunk can be fixed.

I know people recommend stretching exercises - a lot of people saying this suggest leg stretching rather than overall body stretching. I think overall body stretching would be more beneficial though - I don't think you can just isolate one part of the body like that - from my experience of stretching, having a routine which includes back stretches is important in helping and making effective the leg stretches you do. This is why I think yoga would be better than just leg stretching.

I think walking is really good preparation. It is good for general body conditioning - cardio / muscle - but it won't make your legs insanely strong / give you thick bones