1. which mine you want depends a bit on the surrounding sectors, if you want to trade yourself.
platinum is valuable and can net you some nice profits.
If you want to start a trade emporium though, coal and ore mines can be used to create steel, which is an ingredient of many products.

2. traders spawn once enough stations are in a sector. the trader limit gets raised the more stations are built (per sector). IIRC the formula was (amountStation)/2 -1. that means you need at least three stations for traders to spawn. keep in mind that currently traders only trade as long as you are in the system. at least for me, trade wasnt happening when I was somewhere else.

3. Cargo shuttles are used to ship goods between your own stations, so that they can supply each other without you having to haul all the stuff every time.
To use them, place hangars on every involved station. now go to one of the stations and transfer the cargo shuttles and enough pilots to it.
to set the trade route, open the "browse goods" window (the one where you can buy/sell at npc stations). there is an additional tab with a cog icon, where you can:
- set the shuttles to bring this station's goods to a station that needs them
- send out the shuttles to a station that produces goods required in this station

that cog icon tab also lets you upgrade your station to a bigger variant (the whole s, m, l, xl stuff) which increases the amount of simultaneus productions happening.
also you can set there that the station allows traders to dock and sell/buy goods

fantastic, thanks for the help

can i build cargo Shuttles only with iron? or is there a button i dont see so i can upgrade it to ... maybee trinium?

i dont think there is, i tried to make some myself, but they default to iron, i atleast did not find a way to change it since they dont want weapons