I would just go with the neck you have. Its already carved. May as well give it a crack.
On the tone bars and finger braces - go ahead and add 1 tone bar and 1 finger brace on each side. Its a very thin cedar top - and cedar already tends toward soft/light.
Bracing wise - how tall is it now? I would shoot for no taller than 1/2"/12mm for a guitar this small. Taper the braces to nothing in the lower bout before they get to the linings.
Be sure to cap the X-brace joint with a scrap of brace wood. 2mm thick is sufficient.
On the bridge. Since you are already this far along - just use it. If you have a problem in the future - you can replace it.