1) Yup. That's perfectly okay.
Quote from this article on my website:
Blitz's LoadAnimImage command doesn't care how your animation frames are positioned within the image, as long as it knows how many frames there are and what size each one is.. You could give it..
.. or..
.. or..

.. or even..

.. (as long as the last two frames are blank) and Blitz will produce the same results.
2) DrawBlock you mean? If there will never be a Masked Transparent pixel in your sprite, then yeah, feel free to use DrawBlock.
Quote from this article on my website:
Blitz's LoadAnimImage command doesn't care how your animation frames are positioned within the image, as long as it knows how many frames there are and what size each one is.. You could give it..
.. or..
.. or..
.. or even..

.. (as long as the last two frames are blank) and Blitz will produce the same results.
2) DrawBlock you mean? If there will never be a Masked Transparent pixel in your sprite, then yeah, feel free to use DrawBlock.