You can port any number in to A&A for £12, then pay £1.20/month.
You can connect a normal landline phone to VoIP using an ATA (Analogue Telephone Adapter) -- I use Grandstream HT801, but found you need an RJ11 -> BT adapter with ring capacitor
You can receive calls from any number, including mobiles. Outgoing calls to mobiles are 4p/min; they are listed here
. If you choose to redirect your 01 / 02 number to your mobile (using A&A web interface), then you will pay the 4p/min to redirect to your mobile and the person calling you will pay their normal rate for dialling a landline.
Yes, you can redirect to multiple numbers at once.
A&A provide SIM2SIP that provides you with a normal SIM card that connects directly to their VoIP platform:
£5 for the SIM
£2/month SIM charge
2p/min to dial out + the normal p/min for outgoing calls (1p - 4p/min for normal numbers)
2p/min to receive
calls via the SIM
2p/SMS to send an SMS via the SIM + 7.2p for an outgoing SMS
2p/SMS to receive
Mobile data is a whopping £24/GB (2.4p/MB)
For personal use, it would probably be cheaper to get a basic SIM card (e.g. Smarty) and make / receive / forward calls & use data via that SIM card.