$7.00.  YOu should tip on subtotal of bill including the salad that you got for free.  Bill around $32.00 pre tax.   That would be about $6.40.  I would round up to $7.00.  If service is great, I give more.  A couple of dollars to me is not as important as a couple to your server.

Suggest 3 wheeled with 2 wheels in the back for better balance.  Like the adult 3-wheeled tricycle.  Whatever it would be easier on 3 wheels.  I would buy one for errands.

Depends on your taste.  I was shocked but I like rock and roll.  Who controls the votes?  The age group would probably tell more.