Anita Vitrified tiles by themselves do not particularly allow the walls to breathe, and hence are prone to cracking. That being said they do not collect moss either. If you are however set on using these tiles, I suggest you use them in a mosaic fashion, where smaller tiles or broken pieces are used. This will allow the wall to breathe, though the moss collection might be more due to the greater amount of grating.

Stainless Steel 304 Grade is the most suitable for your application as i have checked your site picture, if you use Glossy finish then there is no chance to get rust and will have a life of 7 to 10 years minimum, but also keep in mind do not attach the gate with Iron Knails or any Iron fitting as in contact with iron the stainless steel will aslo catch rust.

Tushar, try HPL Sheets. They are made for external finishes.

I really liked the indirect lighting and the bar light fixture.