Server configurability with Asterisk with GSM gateway?

Question

Asterisk

This question arose after solving this: How to optimize telephone costs by making calls through CRM?
For myself, I want to understand what options exist for configuring Asterisk when using a GSM gateway. I ask for advice from Asterisk experts
So, given: I
plan to buy a gateway for 4 SIM cards. Operators call through the CRM interface, mostly outgoing calls. Each SIM card has a package of minutes, pronouncing which, the number is blocked. In this regard, there is a need to change the used SIM card to another.
The questions are:
1) Is it possible to assign to each operator not a specific phone number, but a specific slot for a SIM card in the gateway?
2) If so, is it possible to replace the SIM card in the gateway without turning it off?
3) Is it necessary to restart the server with Asterisk when changing the SIM card?
4) Is it possible to bind 2 SIM cards to each operator, when the first one is blocked, the system automatically switches to the second one? (I consider this option last, since it will be necessary to buy a gateway already for 8 SIM cards)

Answer 1

1. Yes
   
2. Model dependent
   
3. Not
   
4. Yes