Questions about "Pet"

Hello guys, newbie here! Started fresh yesterday.
Please help me answer a few (dummy) questions:

- What is the difference between a "donor" pet and a "normal" pet? Can vote cash be used to buy donor pets?
If not, how to do the "donor" thing? I can't seem to find it anywhere on the homepage

- I saw some pets with "0 days of magic" while others had "90 days of magic." Does that mean those "0 days" are permanent pets?

- Is there no "item looting" equipment for pets? Or where can I get them besides the cash shop?

- Should I be concerned about which group of pets to buy? (I remember that we can have up to 2 or 3 pets at once), or is it purely random?

I tried researching quite a few hours before posting this, but maybe I was too dumb...

Thank you in advance to anyone who is going to spend some time to help me out! And if my post is violating any rules, please let me know so I can adjust asap!