Hi Joe
I have used Zymol a lot on a few different cars, over the years so I'll give my 2pence worth!

I have used Zymol Carbon on my black GTI, and although its good, its not worth the £49 I paid for the pot. To use the wax properly, you have to use HD cleanse first, either by hand or machine, which cleanses the paint and helps the wax bond. I found HD Cleanse ok to use, but there are a lot better products out there.
The wax is a little difficult to remove, even after following Zymols detailed instructions. It smells nice, gives a reasonable finish, and has to be kept in the fridge (seriously)!

You only have to use a little bit, so I reckon the tub would last a normal owner easy 2-3 years if you wax once a month.
I did my GTI twice with Zymol, but found it just didnt last, even using their shampoo. Its still sat in the fridge almost full! I'll use it as a spare wax for anyone who specifically asks for Zymol (I'm occasionally doing friends cars now for a few quid!)
If you want my advise, leave the Zymol products alone apart from their Tyre preserve
http://www.monzacarcare.com/products/?category_id=6111&search_mode=view_item&product_id=1534&start=0&search_term=Enter%20search%20termand their Seal rubber preserve
http://www.monzacarcare.com/products/?category_id=6112&search_mode=view_item&product_id=1492&start=0&search_term=Enter%20search%20termA far better product IMO is Zaino. Buy a tub of Z2 with ZFX accelerator, then top it off with a spray of Z8. I use this now and it looks fantastic and lasts for ages. Its easy to use, wont mark any rubber or plastic, and you only need to use a tiny amount so it'll last yonks!

182_Blue recommended this to me, and he knows his stuff. There are pro detailers on DW using it, with amazing results and durability.
As for claying, I'd wash the car first to get rid of any dust/dirt, then give the car a good going over with the clay. Use the quik detailer to help the clay slide over the paint. You'll be amazed how much junk it takes off. Warm the clay up in your pocket for a while and it works better IMO.
DONT use any that has dropped on the floor, dump it as you WILL scratch your paint with it. It picks up bit straight away.
Then give the car another wash after you have finished, it'll look as good as new and your paint will be really smooooth!

HTH bud.