Why dont you buy some mp3 that is supported by rockbox
Try phone finder, I’m not sure it has all the filters you need but a good start
Strange there are some on the XDA but unofficial.
You need play services probably. Not sure you can install only one so you most likely need GAPS, try Nikegaps or find some other GAPS providers. You might need root or adb
If you have USB debugging on then yes. If not try to see if you can mirror display with USB and a TV/monitor. If that doesn’t work a USB mouse will have to do if you know that layout of your phone. A keyboard could also work for the pin. I always suggest leaving USB debugging enabled and paired to your computer so in such cases you could just do
adb pull /storage/emulated/0(or another number if you have different users or work profile /path/to/desired/location
This way you’ll pull all the data from everywhere and delete what you don’t need. With USB debugging enabled you could also use SCRCPY, it’s a neat tool that’ll mirror your screen and you can control the phone with computer mouse and keyboard. If you do want to try and enable it’ll be in Developer options/settings, if you have them enabled if you don’t you gotta press on Build Number in your about phone section in settings.
If your rooted with magisk try nikgaps. Also you could try installing LineageOS with GAPS
No you dont need root to flash, but if you install magisk you need to flash the patched boot image therefore have bootloader unblocked which is needed. What I meant is that if OP decides to root with Magisk it’ll just be easier to install Lineages OS(if his phones are supported) than to search for the firmware file to extract boot image since Lineage offers it already extracted
Can you root? If so then why not try Lineage OS. The phones seem old and a lighter OS wouldn’t hurt. For battery you can try ACCA (requires root) or Accubatery Also depends on region but 3G gets taken down. WiFi and internet are dependent by tower distance and by how many WiFi clients and networks are around. Try WIFI widget handy tool. Cpu-z to check clock and thermals, ram usage and clocks. I do recommend installing Lineage OS and there are magisk modules if you’re willing to try, they might work they might not.
Or Nier franchise