Yes, that could be possible. If yes, there will be a significantly higher charge be-cause the effort is significantly higher too.

Yes, that is possible, but there will be an additional charge of 9% for the service because that is the additional effort required.

Yes, that is possible. There is hardly any difference to provide another 0.009% availability.

Ask them for the reasonable downtime they are willing to absorb. If it is more than 60 minutes in an entire year, explain how the current SLA meets that requirement.