Hello Katie Wu,
The part number nomenclature is explained on Figure 1 of the i.MX6Q and i.MX6QP datasheets (links below).
https://www.nxp.com/docs/en/data-sheet/IMX6DQPCEC.pdf
https://www.nxp.com/docs/en/data-sheet/IMX6DQCEC.pdf
The rest of the markings contain other information like manufacturing dates and there is not a public document explaining them but if you need more information regarding the parts manufacture data you can contact your FAE, Distributor or Sales contact.
As for packing information it is given in the Part Details page for each part number (links below). Some parts are available in Tray and Tape and Reel. If you need the dimensions of the packages (either tray or tape and reel) please open a Case asking for the details for the desired part number.
https://www.nxp.com/part/MCIMX6Q5EYM10AE
https://www.nxp.com/part/MCIMX6QP6AVT1AB
I hope this helps!
Regards,
