Obviously all different makes and models of cars use varying methods and locations for fixing bolts or screws for lights, bumpers etc., but with a little examination of the items concerned most mainstream models can be dismantled without too much trouble, rusted and hidden fastenings notwithstanding.
Body side mouldings can be fastened by either press-on clips, nuts and screws from the inside of the panel, double-sided adhesive tape, or occasionally a combination of these.
Glass and windscreen mouldings are best left in place unless the operator has experience in their removal.
Try not to get carried away and remove too many parts! and if in doubt about anything, either don't do it or get professional advice.