Hello Pamski -,
Below is the response to your queries.
1) "Review" action is something to verify the details submitted in the PR before go for approval or rejection action. It ensure an additional document monitoring and verification scope in the system.
Better to set this before the "Approve purchase requisition" step. Once the PR is verified, it will got for approval.
There is no restriction in selecting both these options. You can also directly select the "Approval" steps without passing the document through review process. When the approver receive the notification for approval, he/she can go through the entire document as a part of review too and then take an action to approve or reject.
2) "Owner" is the person who created this workflow. The same owner can be set as an approver too.
3) Yes if you select the users in the "Assignment" section, then they will be responsible to take approval or rejection action in the workflow.
However; you can further decide whether the workflow will work on single approval basis or based on multiple approval where every single users you selected as an approver in the Selected Users section, should be responsible to approve or reject the PR once submitted. Once you set the approver, this validation you can set in the Completion policy.

4) Yes this support in both PR and PO workflows. You can define this in Condition section.

You can also set amount matrix in PR line also.

In any ways; you can also define "And" "Or" as per your requirement.
Kindly check and review.
Best regards,
Sourav Dam
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