Retrying camunda start-instance and delete-instance rest api

I was using camunda-spring-boot-rest api 7.9.0 version.

Qn-1. Is that possible to set retry option for starting and deleting process instances?

Qn-2. In a scenario, i have to delete the submitted process-instance and need to start new
process instance for same businesskey
.

Suppose let say, I might have 3 process-instance need to be deleted for 3 various business key(Bkey-1,Bkey-2,Bkey-3) and need to start a new process instance for same businessKeys (Bkey-1,Bkey-2,Bkey-3).

Lets say, I was iterating through list of business keys incremently like:
step1: Delete processinstance for BKey-n
step-2: Start processinstance for BKey-n

Qn-3. In case, my list size would be 3, and deletion fails on Bkey-1 iteration due to network failure or connection timeout, will camunda retry the request again?

Qn-4. If retry is possible how many times will it retry and time period within retry if it provides more than one retry attempts.

Qn-5. Is the retry option is synchronous or asynchronously executed?

Qn-6. Retry option of failed requests by camunda is possible for usertask and manual task also or only possible for service tasks?