Indivision is not a graphics card, it doesn't give you any additional video modes, only allows you to use the original Amiga modes on any VGA CRT/LCD display, hence there is no memory on it (no need, Amiga chip memory is still used).
And yes, it can cope with any Amiga mode including the early startup screen.
Not strictly true. It does have memory onboard for the trickery it uses to double the frequencies.
The memoery isn't available to the Amiga however.
And it does support screenmodes not available on the amiga. The highGFX modes
