How to deal with this area?

There used to be a stair case on the back of the house in this area. I'd like to tackle building a new set of stairs and replacing the old door. What's the best way to deal with the old aluminum siding? The new stairs won't match the old location and I'm not ready to do the siding on the entire house yet. Also, should the siding continue past the future ledger and down? I'd appreciate any comments or advice about pitfalls I might encounter.

Thanks!