Your wheel trim is based on the wheel rim size which you will find on the tyre i.e. 205/50/R15/T. The R15 is the rim size but could be different for your car. As for the spray paint, if your car is not metalic finish you could try T-Cut which is for cars. you polish it on and it removes a fine layer of paint and should get rid of the spray as long as its not too thick.
Well the wheel trim thing has been answered. As for the paint this could be easy or could be very expensive. If the car is fairly new and unlikely to have already been resprayed then a clean soft cloth and a bottle of cellulose thinners will do the job. Test a patch that won't show first say under the boot carpet or bonnet. If it doesn't effect the original paint then wipe the paint directly. Soak it first with a wet cloth and then wipe off quickly and once completed wash the panel immediately. Wax the panel to complete the job.