Hi, I am new to file conversion and have some questions.

I tried to convert a music file from Apple Music to FLAC. The file is converted with a compression at 24bits and the sampling rate is at 44.1kHz

How do I know if I should use 96kHz or 44.1kHz?
Can I convert the FLAC further using uncompressed lossless encoding? Will it helps in the audio file in any way apart from the larger file size?