Some asterisk questions

I've just been learning about asterisk for the past few weeks and will be setting up a test box to play around with some soft sip phones.

There were some things I couldn't figure out though no matter how much I searched. Maybe I'm using the wrong terminology or something. So I'm asking here and hopefully someone can help me out.

First Question:
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Lets say I have one asterisk server and one (lets say) 2 line SIP phone. I have 2 (or more) channels to a voip provider and a dozen DID numbers.

When a call comes in, I'd like it to ring the free line on the phone, display the CID info of the caller, as well as what DID number was dialed and possibly a line of text related to the DID. Having different ring tones based on the dialed number would be nice too.

Is that possible? What's a good phone to use in that case? The Grandstream GXP20XX look pretty good and have large displays.

Is there some sort of help page somewhere on how to send messages to the phones?

Second Question:
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This one is similar. A bunch of channels to VoIP providers or POTS lines with a bunch of DIDs. Side question first. If I have 10 numbers and 5 lines from the same provider, any of those 10 numbers can come in on any of those 5 channels right?

This scenario would be something like 4 receptionists handling all the calls. Call comes in, goes into a queue (or ring group?) during normal business hours. One of the receptionists answers the next call in the queue and the number that was dialed is displayed along with a text description and the CID info of the caller.

Then the receptionist can use the soft keys to either forward it to voicemail for an extension associated with that number, forward it to an internal extension (will be setting up hot desking but I think I understand that), or forward it to an external number. That number will be associated with the DID number so they just need to press a button.

Think of it like a virtual office setup. Call comes in. Answered by shared receptionist pool. If person is in office forward to their extension, if not, forward to their other phone number, if not normal business hours forward to voicemail and the receptionist doesn't have to look up the users extension or other number and when they pick up the phone it has the number dialed as well as a message saying this is for Business XYZ, Inc. All without having to have those phones with the add ons for extra lines.

Is this possible? What are good phones to use in this situation?

This is all academic now, so I don't need full details, but some pointers in the right direction would be nice.

Thanks