80x25 is by far the most common standard for console size

AFAIK, no, the most common standard for console size is 80x24, which came from the VT100 and is used by default on terminal emulators like xterm or the GNOME terminal.

No. It's the standard CGA/MCGA/EGA/VGA/SVGA int 10h mode 3, where on VGA/SVGA cards it was a 80x25 console comprised of 9x16 glyphs (8x16 really, where the right-most bit is duplicated) for an analog effective resolution of 720x400 in 4:3 aspect ratio.

Historically, when processors, motherboard buses, and video cards of physical machines were much slower, text modes were accelerated ways to write text such that they were much faster than writing and scrolling text graphically in a video framebuffer. Interestingly, on VGA/SVGA cards, it's possible to do double buffering of text by page flipping but it's pretty pointless even on real hardware.

Emulated hardware generally doesn't suffer from tearing effects that happen on real hardware where large updates (mostly in graphics modes rather than text modes) aren't synchronized with the raster scan and end up looking bad by showing partial portions of the previous frame and current frame while an update is happening. In graphic modes, this was mostly eliminated by double- and triple-buffering with precisely-timed page flipping on video cards that had enough memory to have 2 or more whole frames..

(B800:0000 and A000:0000 are permanently etched in my brain.)

Thanks