3.) The standard NIfTI 16-bit data type is 16-bit SIGNED integers - this can losslessly encode values from -32768..+32767. This is typically fine, as most classic MRI systems use 12-bit ADC (range 0..4096). However, it is clear that your software is set up to convert to 16-bit UNSIGNED (0..65535). This is really way beyond the SNR expected for EPI data, but it poses a problem for true lossless conversion. In this situation my software provides you with two options:
 a.) save as unsigned 16-bit integers (UINT16): this keeps the raw data from your scanner unchanged. However, this is a legal but atypical NIfTI data format so subsequent tools may fail.
 b.) save as 32-bit floating point (FLOAT32): this is a standard format that has ample precision. However, the files will require twice as much disk space and will probably require more time to process.