Ugh... That sucks. When I was in the store buying all my gear for the first time I listened to a clerk talk a guy out of buying a white jacket for this exact reason. I wish I could help you but I got nothing. So sorry.
As far as leather goes you can use the same process you mentioned. Soapy water, mild soap that is, and any old cloth. My son went through the stage where he was hell on my leather interior. Nothing like a chocolate milk, juice box, smashed skittle cocktail to make the job fun. Just make sure you keep it conditioned. This will help keep the stains from setting and shed water when you're caught in the rain. I would condition it even before the first wear. It also helps soften it up so it contours to your body better and makes it more comfortable to wear. Hope you enjoy the new jacket!
As far as leather goes you can use the same process you mentioned. Soapy water, mild soap that is, and any old cloth. My son went through the stage where he was hell on my leather interior. Nothing like a chocolate milk, juice box, smashed skittle cocktail to make the job fun. Just make sure you keep it conditioned. This will help keep the stains from setting and shed water when you're caught in the rain. I would condition it even before the first wear. It also helps soften it up so it contours to your body better and makes it more comfortable to wear. Hope you enjoy the new jacket!