I would suggest developing your own coding system for sure. Not difficult, you just have to decide on the best format. For example, let's say you are Drop Shipping a torch.
I would start with something like a code to id suppler, gives you the flexibility to id multiple suppliers for the same product. I wouldn't think that you would need to code the products for each individual sales platform, however that would be easy enough if you felt it was required.
So, if I was Drop Shipping a DVD player from a JVB Products, my code would be something like JVB0000. If you wanted to tighten that up a little more, you could also ad a country code or even state code fro the supplier. So if JVB were from California, then the code would be JVB-US-C-0000, and so on.
If you are selling more than one DVD player, then ad in a model code, so then your code would be something like JVB-US-C-12-0000
I always find it better to code in more information than less, it keep each product very clearly identified.
In regards to email address, I suggest using an email account you get from your website host, unless you don't want some people knowing your website, but it's usually a marketing advantage to get your website URL out as much as possible, and an email address linked to your own site is an excellent way of doing that.