Yes, but they do not compensate you based on your lost revenue, they compensate you based on how much you spent with them. The best you can get from them is a refund.
Depends on the SLA. Usually you negotiate an SLA to cover much more than a refund of the missed service targets (but with a fixed/known ahead of time cost for breaching the SLA).
I would say even smaller; but more than 90% of those SLAs will have explicit remediation and compensation clauses, hence “usually” wrt. to negotiating an SLA.