To answer your questions:
- You can enable racially locked techs via modding (see below guide)
- You can replace emblems via modding but there isn't a way to offer choices in game
- The game is limited to 11 races maximum, so you can replace any of the 11 slots but not add new ones via modding.
Code:
To enable techs via modding:
1. Make a new folder let's call it "Unlock Techs" under
C:\program files (x86)\Steam\steamapps\common\Horizon\mods\
2. Create a sub-folder "races" in your new folder
C:\program files (x86)\Steam\steamapps\common\Horizon\mods\Unlock Techs\races\
3. Launch Horizon and make a new race custom template using the Humans (race04) as an example, as default. You can edit the template further later. Close the game.
4. Copy the race04 template folder from
C:\program files (x86)\Steam\steamapps\common\Horizon\races\
into the mods folder you just created
C:\program files (x86)\Steam\steamapps\common\Horizon\mods\Unlock Techs\races\
5. In your mods folder under templates you can delete the .har files and name your template.xml and template_lang.xml to default.xml and default_lang.xml. If you don't rename them it will work but won't be the default template.
C:\program files (x86)\Steam\steamapps\common\Horizon\mods\Unlock Techs\races\race04\templates\
Now you can edit this default.xml using a text editor like notepad:
scroll halfway down you will see the "StartingTechs" section and replace techs with the value "-15" to "-1". This will make them available without adding them, to add you can set it to "1".
Save and start Horizon. Click the Mods button and enable your new mod in the list. Then Restart the game.
Your modified race template is now the default for that race and you will have racial techs available to choose.. You can further modify it in-game race customization.