So my question is: Is there a plan to split up the players (PC) interface from the GM NPC interface so each players can manage they attack, initiative, damage table, etc.
No. For those people that have the paid version, doing this would slow things down immensely. The whole idea is that this is GM helper software, where nobody ever has to manually look up a table. The software does all of that for you.
The free version is demo software, to show you exactly how the software works, with a few free tables only. If you are using the free version it will not greatly speed your game because as you have said yourself, someone still has to look up all the attack and crit tables manually. What you are asking
may help the free/demo version, but since it stills mean entering all attack and crit results manually into the attack panel (whether by the GM or player), it defeats the main purpose of the software. You might as well go back to pen and paper.
That answers the "damage table" part of your question. Regarding initiative, I don't see how players can help with this at all. All init modifiers are already within Minion for each PC and NPC so the software does all of that for you. Players can't help with initiative.
Regarding "so each player can manage their attack", again Minion has all attacks for all PCs/NPCs and it remembers each character's last weapon/spell attack. If an attack needs to change, the GM chooses from a select box unique for each PC/NPC which lists their attack modes - about 2 seconds for the GM to change. Allowing the Player to choose their attack will simply slow down the game, since every attack would need tablet/device interaction from every player. We'd end up with the GM saying "Pete, you haven't chosen your attack yet", etc. Choosing attacks is something that should have been pre-declared at the start of the round anyway. A good GM will remember the declarations and when Minion says initiative for a given player, the GM would already have ensured the right attack is shown on the Minion attack panel.
