TF micro cards come in various sizes for data storage, and depending on the size of the card and of the file to print, the simple answer would be yes, multiple files can/could be stored on a single TF card, the Ender3 has the facility to scroll through the card and to pick which one to print.
My preferred option, somewhat long in the tooth in years as far as computers go, never trust the storage medium for long term continual use!
I still have stuff stored that originates back to the 1980's including my first ever program file that was written in BASIC on a Sinclair ZX 80, (
ZX80 - Wikipedia) which eventually became a commercial program for a Blue Chip company listed on the London Stock Exchange.
I keep all important data and files in off/on line data storage, local as in hard disk, SD Cards, USB sticks, CD/DVD writer, external hard drives either attached to a computer or hung off the back of the router, or on the Cloud, Google Drive, Microsoft One Drive, etc, free to store, my kind a price.
As far as 3D printing goes, I just select the files I need, store them locally, and either if using Windows 7 connect via USB, or copy onto a blank formatted TF card and away I go.
As said, long in the tooth, prevention is better than cure as far as storing data is concerned, equally I save modifications to any file as Grandfather (the original file) Father as (the modified file), and Son as (the working copy file).
As for the actual printer, I trusted Mike's judgement and his real world experiences, so I would give the Ender3 a resounding yes.
For suppliers and supplies, again I trusted the judgement and knowledge of a very dear long term friend, who is/was a retired Engineer with some 60 odd years as a draughtsman, CAD designer, CNC designer and operator, and now a fully fledged upstanding member of the 3D printing community.
My machine and supplies came from here........
Creality3D Ender 3 3D Printer
PS: Go for it.........can always blame Mike at a later date, his shoulders are broad enough!