I would like to ask some questions for a journey with reference to the following example:

If I purchase a point-to-point ticket from Grindelwald to Zermatt, can I stop at Interlaken OST for a while? I have searched the website of SBB but could not find any information for this scenario, although many people say it is allowed.
Will the cost of a point-to-point ticket vary with time? If I miss the train(s), am I allowed to take the next train according to the search result on SBB website and would not incur extra charges / being fined?
I understand that super saver ticket only applies to a specific train number. Thank you in advance for your help.