I literally know nothing about this area, so let the research and knowledge begin!
Military
Geography
The ecosystem/climate of the area is somewhat alpine in the highlands, and rather warmer (though still generally temperate) in the lowlands. Colchis (roughly speaking, the western lowlands of Georgia and Abkhazia) and Caucasian Iberia (the eastern part, comprising what is now eastern Georgia, some parts of northeast Turkey and wester Azerbaijan) were separate kingdoms (as indeed they're separate provinces on the RTR map.
I'll definitely be recommending changing the cities, though I want to do some more work before telling you what the city for the Colchis region should be - it's difficult because it's quite possible that the largest settlements were the Greek coastal ports like Phasis, but those were semi-detached from the actual Kingdom of Colchis.
OK, so Vani (https://en.wikipedia.org/wiki/Vani) for Colchis and Mtskheta (https://en.wikipedia.org/wiki/Mtskheta) for Iberia seem to be the most obvious choices. Vani should be at (213, 146) or (214, 146). Mtskheta should be where the current "Mestleta" (a misspelling possibly?) is located though ideally a bit further south (see my comments regarding the Kura river below, it's not actually that close to the upper Caucasus range. It actually sits on the river of course, but to the river's north I guess makes more sense. I'd put the port for Colchis at Phasis, which is roughly right where it is.
The geography of the region needs work. Colchis should extend at least one valley further south, and Iberia should extend a lot further south to pull in a lot of the mountains that actually formed ancient Iberia (most of which are now in the overly large Greater Armenia province), but lose the bits north of the upper Caucasus range and the eastern lowlands which are more naturally part of Caucasian Albania (which should also take in some of the plains from Greater Armenia to encompass what's now Azerbaijan more closely). This whole Caucasus area shouldn't look so desertified either, it's a very green/fertile area (swampy in places in the lowlands). I'd also pull the Kura/Mt'kvari river (the long one that flows down to the Caspian) a tile southwards along the upper curve.
Possible capitals could be Kutaisi or Tsikhekhuji imo...
And the ports could be either Phasis or Dioskourias...
So, culturally it's a bit hard to say all that much about Colchis because it was rather a mix of the inland Iberian and the coastal Greek cultures - the flavour of the province is very much "semi-hellenised Iberians" (and the Iberians were an incredibly mixed bunch). A lot of Colchian towns, even inland, would have looked and felt pretty Greek in our period, though the language, coinage and religion would all have been Georgian.
Religion
The main religion in both Colchis involved the pantheon of the "Seven stars":
- Sun
- Moon
- Otarid (Mercury, star of learning)
- Aspiroz (Venus, star of beauty and healing)
- Marikh (Mars, star of war)
- Mushtar (Jupiter, star of justice)
- Zual (Saturn, star of adversity)
The associations clearly have some relationship to Greek deities, and it's hard to say whether they may have been altered somewhat post-hoc by writers with a strong awareness of Greek traditions, but that's the basic pantheon.
Exports
Flax, hemp, pitch and slaves are all recorded exports from the area - as are pheasants (or at least pheasant meat, something of a luxury food), which apparently derive their name from the area (the greek is Phasianos or Φασιανος, aka the bird of Phasis, the main Greek port colony there). There's evidence of gem working, and the production in large numbers of (low quality) silver coins.
http://www.twcenter.net/forums/showthread.php?686893-Caucase-Iberian-(-Kartli-)-and-Colchian-(Egrisi)-units
Researches in Iberia-Colchology by Gela Gamqrelize
The greek colonisation of the black sea area by Gocha R. Tsetskhladze
There are also other good books and articles by Tsetskhladze. Plus Pontos.dk has good publications for the area