See pages 103 to 105 of the Tier 4 modernised guidance for caseworkers:
https://www.gov.uk/government/publicati ... sed-system
You appear to have a lot of questions about your Tier 4 application. The international student adviser at your university is best placed to offer detailed, individual advice which is free, impartial and professionally regulated.
People posting here are well-meaning, but they may also be unqualified and unregulated. I do not give immigration advice, just refer to Immigration Rules, guidance, other online content and to your sponsor to help you answer your question.