Hello, Ed-Zero.
Thanks for the kind words. Now, to answer your questions:
1. It is not quite as you have described. Lets assume you have a Seraphim who is level 10 and you put 10 points in her Celestial Magic focus skill. Then you can choose a total of 3 modification points for any of her Celestial Magic combat arts. Lets assume you plan to advance her Radiant Pillar. Now it doesn't matter at all if you use the editor and choose 2 bronze modifications and one silver, one bronze and 2 silver, or even 2 gold and one silver AS LONG AS YOUR TOTAL NUMBER OF MODIFICATIONS DOES NOT EXCCEED 3. You can have a total of 15 modificaction points for any aspect (by increasing aspect skills), so it perfectly safe to upgrade 2 combat arts with all their modifications and one other CA with any 3 modifications. The problem begins when you try to choose more modifications than possible with your current aspect level (eg. if the game allows you to choose 3 modifications and you choose 4 - disabling the safe editing). The game will then tell you that you have 4,2... modifiactions available. Why is that? Sacred does not save the number of total modification points available in the save file (at least I didn't find it anywhere ). It is my understanding that the game always counts the available modifications points based on the aspect skills and substracts the number of modifications used. So if the value is -1, the game reads it as hex FFFFFFFF, and displays as unsigned value 4294967295. Thus the 4,2... points available. The editor shows you -1 points to distribute for your information only (you then know, that you exceeded your total modifications available). It does not store the value anywhere in the file. So forcing it to 0 would do nothing in game. It is one of the main quirks that bug me in Sacred 2, but I can do nothing about it. Nothing other than minding not to exceed total modifications available, that is.
2. Technically it is, but it would require some serious hex editing. With editor it is not possible. Let me explain why. Skills are stored in a save file as simple numbers, so changing them is no hard task. But combat arts, God only knows why, are stored as character strings. For example Seraphim's Radiant Pillar is saved as se_cm_lichtsaeule. se - seraphim, cm - celestial magic (or its German counterpart), lichtsauele - Radiant Pillar in German? Changing it to other CA that's name is of the same length (17 chars) is not difficult. So you could easily change Seraphim's Radiant Pillar with Dragon Mage's Protector (dm_co_beschuetzer). But changing it to Shadow Warior's Demonic Blow (sk_hc_harterschlag) would cause the save to become corrupted - you could not load your toon any longer. It is confirmed, that there are some offsets stored in the save file, that define different sections of the save file and their length. I, for one, do not know where they are, so I cannot change them to correct the new combat art length. This is basically the only problem, since I have confirmed that changing combat arts of the same name length is possible. Note that this is also the reason why you can't add new skills with the editor - you can only replace/modify existing ones, that you chose in game.
3. Please, look here: Link. There is a great item editor by jimbouk. Hopefully you can use it to do what you want.
@PS. Now this is unexpected. Gold modifier should work with typing in a number as well. Maybe after changing focus from it to another text field? But fortunatelly it works with +/- buttons.
Well, I hope the answers I provided are understandable. Sometimes I forget not everyone is a software developer, but I hope what I wrote clarified some of your concerns.
Have fun with the editing.
Thanks for the explanation of the modification points. I did not realize that you needed to have the appropriate level in order to check the additional mod for the ability. That's what originally caused that problem. Thanks for your advice and the link to the item editor (which I'm still trying to learn how to properly use), you've helped me out massively.