FX expressions for SLA and Ticket Assignment

Hello, 

I am currently having trouble with the SLA on one of the ticket types. The process flow for this type of ticket is as follows: 

1. User raises a ticket
2. Ticket goes to line manager for approval
3. if approved, then a task is created and resolved
4. After task is resolved, the ticket is assigned to the Site Head for approval
5. if approved, then it finally goes to the CEO office for approval. 

The only place where the ticket stops SLA is when the ticket is with the line manager for approval and during the other steps (after step 2 is approved) the SLA clock is running.

My Questions: 

Q1. Is there any expression that can be used or any other way to have the SLA clock of the main ticket stop during the approval processes ? 

Q2. Is there any expression that can be used or any other way to have the Site Head Approval (Step 4) assigned to the Site head based on the office location selected on the main ticket. 

Any help in this matter is appreciated.