As long as you’re maintaining sufficient margin your position will not be squared-off, the available margin can be in form of collateral as well. However, any loss you make will need to be settled from cash balance only, else your account will result in a debit balance. If you fail to add funds then your pledged securities will be squared-off to the extent of the debit balance, you can check out this post for more details:
For Options, right. But as Futures are marked-to-market, means any profit or loss you make is settled and credited to/debited from your account on the same day. So you will have to maintain cash in your account to settle the loss in Futures position.