Carrying cost in a Futures Contract

I am very new to futures trading and need clarification on this cost.

I understand that delivery margins are different from intraday margins. My questions are on a different note.

  1. Let’s say in a delivery futures contract the price goes in the opposite direction of the entry increasing the margin requirements than the initial (original) margin. What is going to happen, if the trader neither squares-off the position nor adds more margin to the account expecting the trade to reverse and go as per his call? In this case, will the broker adjust the initial entry price (against the trade call) to meet the margin requirements? Please explain.

  2. Now let’s say in a delivery futures contract the price goes in the direction of the entry. And the trader is not exiting. Due to any unknown reasons, can the margin requirements increase than the initial (original) margin? If yes, please explain with scenarios.

Net-net I would like to know:
3. Apart from the below costs:

are there any other cost a trader need to bear irrespective of the Profit or Loss?