Some questions about Multi-Rate Processing and Polyphase Filtering | FX Book Questions | Forum

I am researching this topic. I have some question need admin makes more clear.
1. If M and L values are not equal the length of output and input are different but as i know, the function processAudioFrame will be call the length of input times so the output will be lost some data point. Is that right ?
2. Can i import an audio wav file then i get the processed wav file? Is that feature : Audio/Midi > Process into WAV file?
3. I try to change M = 8 and L = 4 but there is no difference between the input and output. Please explain to me?
4. I put the wav file with 2hz => T = 1/2 = 0.5s downsample 2 times. So i will have the T = 0.025 is that right? Because i think when we change sample rate we will change the pitch of sinwave ?

Please explain to me.
Thanks.