Probably the best thing to do is use the search facility on the sight and type in key words/phrases.....the wealth of knowledge is incredible and I'm sure you will come across plenty of information to cover the questions you have asked.
Hope this helps,
Vegas Nights is a fab glitter - I put it over nearly everything! I have used it by itself too which looks good - it's got more of a silvery glitter sheen to it rather than yellow.
Also Ambience is a lovely peachy glitter that goes really well over Passion and Tiger Blossom.
I have watched a couple of the tutorials on the CND website and like the kit they say to layer the additive on to uncured shellac.
I didn't get a very good result last night by doing it this way.
I have been layering the additive on to the cured second colour coat then floating the top coat...