Newbie. Need shoes

The toe clips and straps found on most 'spinning' bikes work best with any shoe that has a somewhat stiff sole and rigid/stiff toe box area.

If you could find a lifting shoe or cross-trainer shoe that has a sole stiffener (sometimes spring steel, sometimes a fiberboard material, etc.) and a stiff leather toe area you would going in the right direction for a dual use shoe. The sole might be plenty stiff by the time your orthotic inserts are added...something to think about.

If the spin bike has pedals with a vertical rear cage plate, you could definitely gain some high RPM stability by using a dedicated cycling road shoe with adjustable slotted cleat. If you go this route you will have to swap back into conventional gym shoes or lifting shoes to go thru the rest of your workout routine. Cycling shoes with raised cleats are barely walkable and certainly poorly suited for ball room dancing, lifting, etc.

Any decent local cycling shop should be able to fit you and your orthotics and until you hit upon a shoe that feels right on your feet, I recommend only shopping in person for your shoes. Your spin instructor can give you advice on what type of shoe works with the pedals found on their Expresso machines..er...bikes.

No, not a road shoe. Road shoes usually have a sole w/o any treads and a big protruding cleat, making them awkward to walk in even for short distances. The big cleat is no good to you as the majority of spinning bikes use Shimano (MTB) cleats, which can be recessed into the tread of a fairly normal looking shoe. You can get anything between dedicated spinning shoes, well adapted for indoor use, or sort of crossover shoes for hiking and cycling. Or one of the MTB specific outdoorsy models with buckles and straps instead of lacing. Sidi Dominato Mega is a roomy shoe which should offer good room for a custom insole. Specialized have fairly roomy toe boxes, but are kinda low across the instep. Performance WRT cycling shoes is pretty much determined first by fit and comfort, second by sole stiffness and a late third by how well the shoe retains the foot when pulling upwards. Personally I like shoes with buckles rather than straps, and straps rather than laces. Straps means velcro, and velcro wears out eventually. Laces stretch more than straps, so fit and foot retention changes through the ride. For spinning class sole stiffness isn't such a big deal. Classes tends to be 45-60 minutes, which in most cycling terms is a fairly short ride. Possible aches and fatigue that would be important to avoid if you're riding (long) races won't really have time to develop properly.