Hi there
I'll start with question 2 first as it's a bit easier to answer. Robots.txt blocks the crawling of a page, but not necessarily indexing. Of course, if the page cannot be crawled it will be deindexed eventually anyway, but if you're getting that description for one of your URLs, Google has not been able to access it and will stop trying to. So that is usually enough, although if you want to remove it as well, you can by all means.
For question 1 - GWT is a bit awkward in the sense that it treats http and https versions of your site as different webmaster properties. Furthermore, if you want to remove a URL on your site, it will always prefix it with the http/https version of your site, no matter how you enter it.
If you added another WMT property that was https://www.yourdomain.com - you would be able to manage that domain as well and thus you would be able to remove any URLs under that prefix.
Incidentally, if you want to block all HTTPS pages from being accessed, you can do that with a special instruction in your htaccess file and robots txt. You can instruct the Googlebot and other bots to read a specific robots.txt file if they visit an HTTPS URL. To do that, you would first add this to your htaccess file:
RewriteCond %{HTTPS} ^on$
RewriteCond %{REQUEST_URI} ^/robots.txt$
RewriteRule ^(.*)$ /robots_ssl.txt [L]
This command basically says "if the URL has https, read the robots_ssl.txt file". You then upload a file called robots_ssl.txt to your root domain. In the txt file you just add:
User-agent: *
Disallow: /
So now, if a bot reaches an https URL, it has to read the robots_ssl.txt file and upon reading that, they are denied access. That would prevent all of your https URLs from being indexed.
That might be useful to you, but if you go ahead and use it please take care to backup all your files in case anything goes wrong - your htaccess file is very important!