Questions regarding Loop project - buffer~ , ~record and push buttons

I am fairly new to MAX and for my setup I want to create a simple looper in M4L but I need some advise to progress. This is my first useful project and below I have listed my wanted functionality and the challenges I have for each. Any advise to get me going further will be appreciated.

1) I need to record a variable length sound file. I was planning to use buffer~ -> record~ -> and then groove~ and load the wav file into a waveform~ object and play with the sound from here. However as far as I understand this model forces me to decide the size of the buffer beforehand and this is not ideal because sometimes I want to record something that is 2 seconds and next time maybe 2 minutes. Please advise any alternatives/workarounds.

2) When recording using record~ I want to do this using an "Live press" button. I.e I want to record whilst the button is pressed down and stop recording into the buffer when the button is released. Any suggestion of an object I can do this with?

3) Same as above I want the groove~ to play only when a button is pressed and loop the selected area in the waveform~ until the button is released.

Thanks