YOu are trying to do too many things at once. Decide what you want, predominantly, and go for that. Then go for the next thing.
So, if the correct lead is most important, do the setup bend and set him into that right lead, and don't worry about him being a little counter bent at first or if he comes off the wall. Just get the needed lead.
Then, address the next thing. Put him back on the rail. Then ask for a bit of a bend to the inside, but be gentle. If he is old and stiff, he may not be able to balance himself so well without being bent to the outside. This is the way a horse canters without a rider on him; bent to the outisde or nuetral. Bending to the inside is part and parcel with asking him to step under with his inside rear leg and lift and carry his rider in a more engaged manner.
But my point, is just keep in the front of your mind the ONE thing you want from our horse, ask for it, get it, give the "thank you" release of pressure and then move on to the next thing you want of him. If he can't do A +B, back down to A only, then go to B and on . . . .