Instrumental sounds in samplers rely heavily on looping. Looping a sound allows you to repeat a section of the sample indefinitely, to create a sustain of unlimited length. An example of this would be an organ sound. Without looping you will only be able to play notes as long as the original recording. With looping, notes can be of any length.
Batch Processor can work on any number of files, and process different files with different settings. Batch Processor is much more effective than rendering multiple files simultaneously, especially when a large number of files are processed. This is because it is more efficient for the computer to process the files one after the other, rather than sharing the processing power between a number of files, all processed “simultaneously”.
Sample rate conversion from a low frequency upwards does not improve sound quality. The high frequencies that were lost due to a low recording frequency cannot be restored by a conversion. When you sample rate convert down to a lower frequency, high frequency material will be lost (this is part of the mathematics behind digital audio). Therefore, do not convert down and then up again, since this will lead to a degradation in sound quality (unless that’s exactly what you’re after).