Myrrhe welcome at CFC!

Thank you very much for your kind words about RARR, RAR and DyP.

Playing on a random 362x362 map is no fun, as usually you will not have enough cities to cover such a random world, as there is a limit of 512 cities in C3C. There exists a 'patch' allowing more than 512 cities, but this patch is not working completely well - that´s why I don´t use it. Even with a random 256x256 map your turntimes in the late game will become long, especially if you use the normal Civ 3 trade-net, with a bigger random world size they are becoming even longer.
If changing something in the RARR biq, please use the editor 1.00 (the unpatched editor coming with C3C vanilla) or the Quintillus editor (here you additionally need Java), otherwise you will loose your scientific great leaders due to a bug Firaxis did while programming the C3C patches.
For enlarging the size of a random map of RARR, the most important settings, that must be changed are in the World Size menue. Here are the settings for playing RARR with 31 civs on a 256x256 random map:
Please note, that not only the world size itself and the number of civs must be changed here, but also the other values in the red circle must be adjusted to the bigger size. I attache that biq to this post.
When importing an existing worldmap, even more adjustments in the settings must be done, as mostly the civs in those worldmaps are not the same as they are in RARR. Even when starting without any preplaced cities on such a map, the starting locations of the civs must be reset, when they belong to a civ that is not part of RARR - or otherwise a new starting location must be added for a civ that is in RARR, but is not in the biq with the imported worldmap. Even more problematic can be the placements of resources, as all these map-biqs mostly don´t use the same resources and the same sequence of the resources as it is done in RARR. If the imported map even uses special player´s settings, these settings must be checked, too. Attached is a screenshot about the Teturkan worldmap you have mentioned and the starting locations that must be changed in central Europe.