BitPim questions

Ok...I plead BitPim ignorance.  I have been to the BitPim website and went through the index and FAQ's.  I have searched the posts on this forum...thanks everyone for their input.

Now to my show of ignorance.  It appears that I can use BitPim to sync my calendar (as well as a multitude of other things).  Does it use the same format as the calendar in my phone or does it load a "BitPim" calendar onto the phone and then sync changes to that?  Will additions to my calendar that are done on my phone appear on my computer (and be saved in a file)? 

I came the Touch from the Voyager...avoided the temptation of the Storm and all of it's problems (didn't really need a Blackberry anyway).  I am trying to get away from carrying a Palm with me also.  I like the new additions in the contacts on the Touch, but am just not comfortable with using the calendar as my sole source unless there is some type of backup.