Apply actions one by one to the whole folder

Let me explain, please. Let's say i have two actions: A1 and A2. A1 finds the string "(.+)" in folder name and writes it to the COMMENT field. Then A2 deletes string "(.+)" from a folder name.
Thus all remaining tracks to be parsed will lose the "(.+)" string because folder is already renamed and its name does not contain "(.+)".
Is it possible to apply actions one by one to the all tracks at once? I mean A1 parses all files and then A2 parses all files. Thanks.

No. As mp3tag does not know anything about folders but treats files on a one-by-one-basis it has to be you who creates the folder-context:
First execute A1, then call A2. No automatism there.

Hmm maybe ... if you should change the workflow.
Step one, two, three, ...: For each file, do all the work on the internal tag-fields of the file.
Step last: Do the changes in the file system.
You can split the whole work into separate Action Groups (at least two groups).

It has been turned out in practice, that also the changes for the file system, that means moving or renaming of files and folders, should be prepared in temporary tag-fields.
Doing so there is the benefit of preview, how the change of a folder name or a newly assembled filename would be look like.
Duplicates and other quirks can be easily detected this way, visually in the list view, or by filtering, before getting into trouble while executing time.
Doing so I have no problems since years with bad file names or unexpected moved folders anywhere.
The rule is: Try it virtual, then do it real.

DD.20120212.1935.CET

So basically there is no one-click-solution and i have to select A1, then deselect A1 and select A2?

Exactly: no one-click-solution. But the actions can be called indvidually either with the help of the toolbar which lists all actions or via the menu "Actions "- which also lists your actions. It is not necessary to use the "Actions ..." dialogue. This should save you the ticking and unticking of actions.