Desktop Workbench... are you serious?  This tool was discontinued years ago so there are no plans to do anything with that at all!  But a few answers wrt Studio:

Unknown said:

1. Regexp handling (or some variation of it) is planned/considered as a function in Search/Replace tool?

Already part of the product, and available within an external app on the OpenExchange called the SDLXLIFF Toolkit.

Unknown said:

2. Custom segment handling is possible before saving the segment/asset to the TM bank?

Create a QA rule to identify these problems as you work, then you can correct them in realtime.

Unknown said:

3. Automatic processing (running a set of search/replace patterns on the segment) of saved TM entries is possible to handle past errors?

You can run batch rules on a TM, but it's not as sophisticated as the capability in the Editor.

Unknown said:

4. Are there any tools in existence or API to write a new ones to achieve 1, 2 and 3?

There are a few TM Maintenance tools on the OpenExchange, and one or two allow SQL statements to be run which might help... but probably not exactly what you want.  There are APIs freely available that would allow you to do many things relating to how you would handle this, and a developer community if you need help.

Regards

Desktop Workbench... are you serious?  This tool was discontinued years ago so there are no plans to do anything with that at all!  But a few answers wrt Studio:

Unknown said:

1. Regexp handling (or some variation of it) is planned/considered as a function in Search/Replace tool?

Already part of the product, and available within an external app on the OpenExchange called the SDLXLIFF Toolkit.

Unknown said:

2. Custom segment handling is possible before saving the segment/asset to the TM bank?

Create a QA rule to identify these problems as you work, then you can correct them in realtime.

Unknown said:

3. Automatic processing (running a set of search/replace patterns on the segment) of saved TM entries is possible to handle past errors?

You can run batch rules on a TM, but it's not as sophisticated as the capability in the Editor.

Unknown said:

4. Are there any tools in existence or API to write a new ones to achieve 1, 2 and 3?

There are a few TM Maintenance tools on the OpenExchange, and one or two allow SQL statements to be run which might help... but probably not exactly what you want.  There are APIs freely available that would allow you to do many things relating to how you would handle this, and a developer community if you need help.

Regards