So yeah, let´s say I want to rename my current main char with the name that my very first "truly engaged" char had, a char that I deleted. Can I?
Yup, as long as no one takes it between you deleting the character, and you changing your main's name.
As long as it's not yet taken, yes you can name a character a deleted character's name. They become available right away. I've deleted a toon before and re-made it minutes after with the same name.
Yes, once you delete a character you can reuse the name. I actually did that when I decided that the hero side was better populated than the villain side and deleted my villain to make her a hero and used the name again.
Yoohoo! I can then stop bein JurgenBlitzII and once again become... Jurgen Blitz, the one and only! Hopefully. Because if someone took my name, I will hang them upon their entrails.
I would wait a day or two before changing names. There might be someone online right now reading this thread and trying to snipe it from you.
K.F. is right. First thing you need to know when renaming toons is to never let anyone know, by any means, the name you're gonna rename your character to. People can use this as an opportunity to get in-game cash/items or PSN Cards or Station Cash Cards from you [yes, they can use the latter as long as the trade doesn't happen in-game or any medium managed by SOE or PSN I think], before they let go of the name you're gonna use.
This exact Scenario happened to a league-mate: He deleted a "Nameholder"-alt and wanted to rename his main directly after that, but the Name was allready taken, when he logged back on his main and wanted to Change the Name. That's why I think, that a Name of a deleted toon should be blocked for the original account for a Minimum time, like an hour or so, before someone else can grab it.