Let me answer your two first questions, one at a time (I'm not sure what you mean by 'how can I monitor my sitemap' so I'll skip it):
Manually submit a sitemap to Google
If you can't use Google webmaster form to submit your sitemap, use an HTTP get request to notify Google of your new site map.
If your sitemap is located at https://s3.amazonaws.com/sitemapbucket/sitemap.gz , first URL encode your sitemap URL (you can use this online URL encoder/decoder for that) then using curl or wget to submit your encoded URL to Google:
curl www.google.com/webmasters/tools/ping?sitemap=https%3A%2F%2Fs3.amazonaws.com%2Fsitemapbucket%2Fsitemap.gz
If your request is successful you'll get a 200 answer with a message like this:
... cut ...
<body><h2>Sitemap Notification Received</h2>
<br>
Your Sitemap has been successfully added to our list of Sitemaps to crawl.
... cut ...
Checking that Google knows about your new sitemap
Open Webmaster Tools, navigate to Site sonfiguration->Sitemaps, there you should see the sitemaps that you've submited. It might take sometime for a new sitemap to show up there, so check frequently.
