Remove specific characters from cells with AppsScript coding

Hi, I'm a bit new to Javascript coding.
I have a sheet called "Sheet1" where column "B2:B" (excluding the header) has strings made up of letters (uppercase and lowercase ones), spaces, numbers and symbols.

I would like to make a script that takes the strings in column "B2:B" and:
1. replaces all uppercases into lowercases;
2. removes numbers, symbols (at the beginning, at the end, in the middle of the string);
3. replaces spaces between words with dashes "-";
4. removes spaces at the beginning or end of the string.

After that, it should put the changed strings back into the right cells.

I attach below an example image. In the photo, the corrected column is placed next to the original one (in D). This is just to show the action of the script.
In the real sheet, the corrected strings must override the original ones in column "B2:B".

Appreciate every help/solution given!


Example.PNG