Your climate differs quite a bit from ours here in the US. Another thing to consider will be the types of herbs that you have. Some are annual, and require yearly planting. In this case, it is best to let them die off for the year. Some are annuals, and will have a different care routine depending on the exact plant in question.
Most of your country resides in the equivalent to our zones 7 through 9. Many perennial herbs will survive, outdoors, with little help.
What I can do, in the meantime, is point you to some articles that will help you with the general care of potted herbs.
https://www.gardeningknowhow.com/edible/herbs/hgen/how-to-overwinter-herbs.htm
https://www.gardeningknowhow.com/edible/herbs/hgen/growing-herbs-in-containers.htm
https://www.gardeningknowhow.com/edible/herbs/hgen/herb-plants-growing-in-one-pot.htm
no additional information
This can present challenges that soil gardening does not. With quite a bit of determination, and paying very close attention to the plants, this can be done.
Here is an article that will help you to get started:
https://www.gardeningknowhow.com/edible/herbs/hgen/grow-herbs-in-water.htm
I have a couple of large rectangular containers (one is an Earthbox) that would make good herb planters. I love your website, by the way. Thank you!
It depends on the herbs you choose and how tall and wide they will get. The plant tags should give you that information. If not, you can look up the plants on our gardeningknowhow.com site to find the size of the mature plants and space accordingly. In a container, it's OK to place them closer than specified for ground use.
Can it be done: put separate herbs in tin pales attached to a piece of wood and hang on a wall inside the house
Sure! I think that this would be a great idea. This article will give you more ideas:
https://www.gardeningknowhow.com/garden-how-to/projects/diy-projects-for-beginners.htm
This collection of articles will help you with the care of herb gardens: