Two short questions about NewDark:

1) Is it still recommended to you use PCX files with a limited colour palette as often as possible (e. g. for legacy support or speed) or is PNG the way to go? Does the compression level matter (or other options supported by that file format)?

2) Does anyone know if it is possible to create anti-aliased text in GIMP while still retaining the colour palette? Even when converting to RGB first, editing and then going back to the palette colors, all text reverts back to a single colour, heavily aliased text instead of an anti-aliased version where the smooth contour is interpolated from the palette table.

As I said, possible legacy support, as in taking the palette limit into account. I don't know, of course, that's why I'm asking what the "optimal way" is.

The palette limit is not really about how many colours the Dark engine could theoretically show on screen but the number of different colour palette families attached to textures which was done to save memory. For example, DDfix enabled 32-bit colours but did not circumvent the palette limit.

You should just use true-colour PNG images for all textures.
There's no reason to use palettised images for anything any more.