We have put together a short survey to capture your feedback in terms of what BT can do when you experience home Wi-Fi issues. We would appreciate it if you could take a couple of minutes to complete a short survey. Read more from here, Fix my home Wi-Fi
If you want to keep your old number, you need a PAC code from your old provider. They are obliged by law to issue one on request. No charge
The number will be allocated to that SIM. You need to speak to the Mobile Team and ask for another SIM and number. (Unsure whether there is a charge).