1. A General would be able to talk about this.
However, conceptually, the crawler goes through your
website and gathers all pages and puts them in a nice format.

Examine your sitemap file and get familiarize with it.

2. You don't have to resubmit to Google. Once a month or so, its
crawlers come to you. If you keep resubmitting so very often,
the search engine might consider it SPAM.