Unless something has changed recently, the only change you can make is to add extra characters, rather than make a file name that's different.
DJI's "custom file names" feature is completely useless.
Lithium batteries gradually lose capacity with age and use.
You can check to see how much capacity has been lost in the battery settings in the app.
Compare the capacity of a freshly charged battery with the number printed on your battery label...
Because they are so slow they aren't adequate for 4K video recording.
You probably can't find such old/slow cards for sale anyway.
No ... V30 will work just fine for you.