1. IN-18 Tubes have been working on our Arduino Shield NCS318 for more than two years.
2. You can buy at shield through this link https://gra-afch.com/catalog/shield-nixie-clock-for-arduino/nixie-tubes-clock-in-18-arduino-shield-ncs318-options-columns- gps-temp-sensor-remote /
3. Full code is always available on GitHUB https://github.com/afch/NixeTubesShieldNCS318

Thank you for your interest in our project.
1. This project NCS3XX uses direct control (full statics) cathodes Nixie Tubes.
2. We have a project on the IN-18 NCT318 + NCM109 Tubes for this project does not require an Ardino board, but this project is fully compatible with the Arduino platform. https://gra-afch.com/catalog/nixie-tubes-clock-without-cases/nixie-tubes-clock-in-18-pcb-assembled-for-4-6-8-tubes-diy-arduino-no-tubes/
3. It will be interesting for us to see your Nixie Tubes brightness control program. We are waiting for your information on your project, it is very interesting.

There are other projects on IN-16, IN-18, IN-8 which are built on the platform of arudino. https://gra-afch.com/catalog/nixie-tubes-clock-without-cases/nixie-tubes-clock-in-18-pcb-assembled-for-4-6-8-tubes-diy-arduino-no-tubes/