save data on MDBT42Q and send it to my device

I read it , and now I guess it "save" me the data.
3 questions:

1. what is the limit of sapce I can use for this ?
   

2. lest say the device work for 2 hours,I got 100 entries - then the battery is unplug.
   is the data saved somewhere? or it got lost?

3. let say that I want to transfer the data to my PI ,
   how do I do this?
   what do I need to write on the PI side ,in order to read the data and then delete the device log?

Thanks ,