Janosch,
I will convey my experience with gold toners, and kalitype clearing. I haven't toned any of my kalitypes because I find that they are not cleared effectively. I will try EDTA soon, I hope that works better.
The longevity of kalitype depends on the removal of iron salts, not entirely on noble metal toning. I wouldn't count on citric acid to completely clear the prints.
The ideal thing to do is to make a border around the negative, so it will mask the edges of the print.You can use ink, rubylith tape is more effective or 120 film backing will perfectly mask the edges.
You will not see the brushed edges in the final print, but if the print is not cleared you will see that the paper is not completely white.
Equally important, the habit of masking the edges of the negatives is also beneficial when toning with noble metals. You will not have unnecessary dmax areas that would consume the most gold or pd of your toner.
All gold toners will result in cooler tones, except for Nelson's gold toner but that would bleach the print so overexposure is essential.
I am not a big fan of gold borax, it is not convenient to prepare immediately and does not have a good shelf life. If you increase the amount of gold, or toning duration it will tone to bluish or purple brown tones.
Clerc's Thiourea toner keeps perfectly well, tones blue to neutral tones. Lawless' Thiourea toner keeps perfectly well, tones purplish brown tones.
Thiourea toners will start working on highlights and shadows equally. Gold-Sodium bicarbonate toner can be prepared quickly does not keep well, tones to cold dark brown tones.
I prepare all my toners one shot, 25 ml for an 8x10 print.
Pd is the way to go for warmer tones. Palladium toning after gold toning will give split tones.
Regards