HELP! TBitmaps under Borland CPP Builder 3.0

I use a TBitmap under Borland CPP Builder 3.0.
first I call ->Mask(...) so now there should only be pixels set or not set
now i need to either
a) find out for a given position (x,y) in the bitmap whether a pixel is set
or not
or, preferably:
b) get the whole data into a buffer of mine, so that i have bits set where
pixels are set and vice versa ...

ciao & thx, max hjek