Synths is short for "Synthetic" which is a man made type of protection as opposed to a natural type of protection like carnauba wax. Synthetic products tend to me more durable and have a higher tolerance to extreme temperatures (which would be very beneficial to your black car)
Between checking out the stickies on here, doing a little bit of research and asking some questions I'm sure you can handle applying some sort of sealant to your car.
As far as protecting your trim pieces from getting white residue on them first of all most synthetic products are designed with ease of use in mind so they can easily be wiped off of the trim if you accidentially got some on the trim. Also, before waxing you could apply a vinyl,rubber,trim protectant type product to the trim. This would make it even easier to wipe off of the trim if you were to get some on it. There are a ton of these types of products on the market. Or another option could be for you to cover the trim up with some painters tape.
