Unfortunately all your options require custom work: It looks like you need an 18" corner cabinet. You will have to modify the last wall cabinet on the left. As I am eyeballing it, you should be able to cut the last cabinet in the middle and then shorten the left section to fit the space of the wall next to the door trim. It's an option that makes the area looks symmetric. Or you can install shelves over the sink. I would not recommend it because it will take the looks away. And the last option will be to remove the last cabinet, shorten it so it fits over the sink and install a single cabinet where the double one was. This will leave a triangle space behind the corner where the two cabinets will meet. You can block the space under it. Hope this helps!

Mukti, From what you described, it seems you need a water softener than a hydrophobic coating. Salt based softeners are good for these issues.

It’s is back painted glass. As a back splash it can be used as it’s easy to clean and maintain. Highly recommended to be toughened. The entire back needs to be cladded in waterproof plywood and then the glass is stuck on to it with special adhesive or silicon gel. Any reservations on using plywood then you can opt for WPC ( wood plastic composite ) which is alternative to play and is totally termite-water proof.

You could go for tiles with design if they are simple ones. if you want plain, you can add some life in the country style with an exposed brick facade or subway tiles. for colours, it depends on how far out of your comfort zone you're willing to go. white is the safe choice, but you can go for blue, green, yellow, all pastel hues