I have a coupon website (http://couponeasy.com)
Being a coupon website, my content is always keeps changing (as new coupons are added and expired deals are removed) automatically.

I wish to create a sitemap but I realised that there is not much point in creating a sitemap for all pages as they will be removed sooner or later and/or are canonical.

I have about 8-9 pages which are static and hence I can include them in sitemap.

Now the question is....

If I create the sitemap for these 9 pages and submit it to google webmaster, will the google crawlers stop indexing other pages?

NOTE: I need to create the sitemap for getting expanded sitelinks.

http://couponeasy.com/

When you talk about sub-domain, it clearly means that it's a separate entity and not at all a part of your website. So, logically it should not be appearing in keyword rankings report of your main site.

You'll have to create separate report for your sub-domain.