This page is based on a section of User blog: Robin Patterson/Col1 FAQ by Toby Douglass. Comments on it should be on its talk page rather than on the blog.
Material copied from http://45mercystreet.com/computing/col94/index.html with specific (e-mail) permission of author (Toby Douglass)
Missions[]
If you decide to attack the Indians, make sure you have a mission in the first colony or two you attack (there's no point in more, since the Indians will burn them all reasonably soon after you begin wiping out their settlements). The reason for this is because when an Indian settlement containing a mission is attacked, converts are generated.
Expert missions are much more likely to cause natives to convert. This can be a useful way to obtain additional colonists early in the game.
There also appears to be some relationship between the distance between a colony and a native settlement containing a mission; the nearer, the more often converts occur.
Once a mission has been established, it cannot be superseded; it is not possible to replace a normal mission with an expert mission. If the expert missionary attempts to enter the village, he will only receive the options to incite the Indians or the cancel his action.
Missionaries are how you communicate with Indians to get them to do things, like attack other foreign powers. Contacting Indians does not expend the missionary.
If a foreign power destroys a settlement which holds one of your missions, your missionary is destroyed. If you destroy a settlement containing one of your missions, your missionary returns to you (e.g. appears on the tile where the settlement was).
Learning From The Natives[]
The Capital of a tribe can train up an infinite number of colonists, unlike the normal settlements, which only train a single colonist.
This can vary from useful to amazingly useful, depending on the skill offered by the capital. If the skill is Farmer, you've hit a gold-mine. An endless supply of instant Farmers, just by sending colonists to the capital. A second example of this I recently came across was the Inca capital offering the Ore Miner skill - wonderful! there are three locations near there were a single colony can support five miners; the perfect mining colony. Having an instant supply of Miners for this is incredibly useful.
A colonist who is a scout who enters a native village has a chance of being converted to an expert. Note that this conversion will occur even if the colonist already possess a skill.
Indian Land[]
City-like settlements (Aztec) own the land for a radius of three squares around the settlement (but not on the diagonals - it's a star pattern, not a square, so the four corner tiles are not owned). Hut-like settlements (Tupi) own the land of a radius of one square.
Indians don't mind you irrigating their tiles; they only object to roads, forest clearing or a colonist in a colony working the tile.
Trading With The Natives[]
Capitals offer about three times the price for goods than normal settlements.
Remember that you pay no tax on goods you sell to Indians.
All settlements will accept trade goods the first time they are offered. This is particularly important with the Aztecs, since you can buy silver in return; and if they like you, at 50 gold for 100 silver - which at the start of the game is selling at 19/unit.
A ship inside a colony can trade with settlements adjacent to that colony; by this method, it is possible to trade with "inland" native settlements.
Some Indian settlements will sell horses.
Miscellaneous[]
The number of a good delivered by Indians as a gift depends on the price of the item in your home country. So for example, at the start of the game, Aztec gifts might be a few pieces of silver. Once the silver price has dropped to 1, their gifts are 50 pieces of silver.
Destroying an Indian Capital generates quite a lot of peace - the Indians basically surrender.