I hope I'm not happy too fast (of course, see edit at the bottom) but Guys, I succeeded
although with some workarounds
1. So I was fixed to use FossaPup
2. I've installed @amethyst suite viewtopic.php?p=12983#p12983 as advised by @mikeslr
3. I've also placed on a desktop shortcut to eject-shutdown.sh from @wizard
4. I've done some customizations as outlined in viewtopic.php?p=99181#p99181
Of course locale and firewall customizations have been done first, I have to synchronize clock as it was two hours late
I've also changed icons' scheme (to minimal) and placement with JWM Desktop Manager - so it was at the LEFT side
5. As I read details about Puppy internals provided here viewtopic.php?t=5818 I started to think, that the most important file is adrv_fossapup64_9.5.sfs
6. So i launched nicOS Save2SFS and saved settings to adrv_fossapup64_9.5.sfs
And I saved it to /mnt/sda3 (it is important as I've used this partition later)
7. Then I launched nicOS Remaster-Alternative as from my earlier trials I knew that *.sfs files can be added
I've checked all options (BTW there is usefull help for each tool)
I proceeded till this window
I experimented regarding copying directories. After all manual copy of /root and /etc don't give anything new.
BUT I've recalled that in 95fix.sh link https://forum.puppylinux.com/viewtopic. ... 603#p17603 provided by @wizard there was step which copied PuppyPin to PuppyPin-norm and PuppyPin-sml.
I thought that it caused that desktop changes was saved during one of my earlier remasters.
I've searched for PuppyPin and found it in my remaster directory /mnt/sda3/PuppyRemaster/root/Choices/ROX-Filer. The important point is that PuppyPin-norm and PuppyPin-sml are old (BTW, I can see that checking modification times are crucial in remastering) so I copied PuppyPin to PuppyPin-norm and PuppyPin-sml in this directory.
Then I clicked OK in Final Check window.
8. So I arrived to this window
And here is obvious error which I've selected. Even though in my first attempt I hadn't copied boot and so DVD didn't booted.
So I decided to copy my adrv_fossapup64_9.5.sfs created in step 6. and copy everything from /mnt/sr0/ without overwriting newer files
Details on image, please look at files' modification times (I've sorted it according to date, newer first)
The window at the left is my NewPuppy directory.
Finally I clicked OK and created my .iso file.
It turned out that localization was completely preserved, along with firefox and it's customization. Even wallpaper (which I've changed) was saved.
But still, Palemoon was default browser. Situation with icons was funny, every one remained on desktop but the automatic-ones (ie. these setup in step 4.) was now at the RIGHT side.
9. So I decided to make a Reamster of Remaster (as I though it will e faster and I'm rrrreallly tired making customizations over and over again...)
As in the remaster the placement of shortcut to eject-shutdown.sh was preserved I deduced that if you move icons manually placement is conserved if you do it automatically then you should be prepared for surprise.
So I reorganized icons manually in the left top corner. As Firefox was still not default I decided to remove any shortcuts to Palemoon from desktop (manually and using JWM Desktop Manager).
Then I tried to remove Palemoon package using "Remove Build-in packages" from menu but it was not successful after remaster.
I've added shortcut to Firefox (drag and drop from localization given by which firefox command), It has default icon for executables (#!) so I set the icon to this called mozilla... in icon directory (I don't remeber where it was).
I've also added shortcut to Firefox to tray using JWM Desktop Manager
9. So again I've remastered system in the same manner as above.
10. Summing-up. Now I have system with Polish regional settings and firewall with only ssh and cups allowed. After reboot the start screen with these settings is not showing.
There are also two shortcuts to Firefox, one at desktop and one at the tray. Palemoon eventually was not removed but now it is "not default" as launching Firefox is easier and Palemoon is buried in main menu.
The system boots 3 min 43 s at my old (bought in 2008) two-core (Intel Core2 duo CPU T5250) computer with 4Gb RAM.
I'm so happy I haven't throw-out this old machine. It is perfect for testing. If something works good on it then it will work very-good at computers in the classroom.
I know this post is complicated and not necessarily tidy. I hope it preserves the method for both other users and me. Feel free to edit it if you find something erroneous. Even though the topic is still actual as not every customization was successfully done.
Edit Of course I was happy to fast. I've tested my remastered FossaPuppy on my home computer and it turns out that Polish keyboard setting was reversed to US. Oh no Is it possible that locale is set differently on different PCs when using the same DVD? Hey maybe there are terminal command which would set keyboard locale so I can make a script for it, similarly as with ejecting DVD? Nevertheless I'll check it on different computer. Super sad
From help to settings:
So still I don't understand...
my keymap contains "pl" so as requested. Why this translates correctly on one computer but no on other?