GTKRadiant 1.4 and below do not natively support Quake 1 mapping, but it can still be done with some clever tricks.
Disclaimer: This is an ANCIENT guide, written in 2003. None of the links work. You will need Aguirre's ConvMap.exe to convert q3 to q1 map files.
A little bit about the different weapons available in stock quake. not really that interesting, just a poorly formatted post where i talk about the q1 guns a bit.
Here's a little bit about the basics of using modern light utilities for Quake Mapping.
MH's tweaked version of Aguirre's light.exe is the only light utility worth using these days. Aguirre's utility added tons of great features giving a lot of control over lighting and MH managed to make it even better by adding in coloured lighting and more importantly, enabling multi-core processing.
The rest of this guide is aimed solely at this version of light.exe, so some or most may not apply if you do not wish to use this utility.