Basically i just want a little advise from people who are a bit more in the know about google than myself.
I am using coffeecups shopping cart creator and recently have been updating and adding new products on a daily basis. When i create a sitemap after uploading my cart updates the URL's for every single product I sell is shown on the sitemap which is great as they turn out decent ammount of google results.
Every time that I add new products to cart creator i have been building a new sitemap so that the new products URL's are shown in the sitemap. Then obviously im uploading it to my server, replacing my old one. Once i have uploaded the new sitemap i am then entering my google webmaster tools account and resubmiting my sitemap so that it may crawl the site again and catalogue the extra URL's.
So basically what i wanted to know is whether or not i need to create new sitemaps every time i add new items to cart creator or whether the new URL's will quickly be automatically added or not. Its not a problem creating a new sitemap though so this i do not mind but if i do create a new sitemap do i then also need to resubmit it to webmaster tools? I have been resubmitting my new sitemaps after each session of adding new items to cart creator but im doing it way to often in my opinion. What should i do if i am regularly adding new products almost every day? Please help. Thank you.

You need to create a new site map each time you add new products, and then upload it to your server.
You do not have to submit the new sitemap to Google as the next time the bot visits you site it will download the new one.

I you look at the sitemap section in Webmaster Tools, it will tell you when it was last download and when it was last submitted.

Same goes for the robots.txt file if you use one.

Thats great, thank you for your help