I have a gestalt fighter/rogue and plan on taking swashbuckler on the rogue half. My question is would taking Daring Outlaw and Daring Warrior be feasible. How exactly would everything stack if it even does?
As a general rule, it is understood in Gestalt play that you can only get a given benefit once, even if both "sides" of your character would improve it. That is, most of the time, it is understood to not be "sides" at all, but just one level that happens to contain the features of two classes in it.
So, if you do this, then any level where you have Fighter, Rogue, or Swashbuckler as part of it will advance these class features. This is not particularly strong if you are intending to take Swashbuckler or Rogue at every level. It would only be useful if you intend to take some levels with a different class (regular or prestige) that would normally fail to advance these features.
IOW, most DMs would not allow you to count as a level 40 Swashbuckler because of these feats.
That said, I personally could probably be persuaded to let these feats stack up to the maximum benefit you could normally get at your level. That is, let's say you did the following:
1: Fighter/Rogue
2: Fighter/Swashbuckler
3: [Fighter-based PrC]/Monk
4: [Fighter-based PrC]/Monk
5: [Fighter-based PrC]/Rogue
6: [Fighter-based PrC]/Rogue
7: [Fighter-based PrC]/Rogue
I have no idea why a person might do this, but let's just accept it for hypothetical purposes. Normally this would mean giving up 2 levels of progress on Grace etc. because you had 2 levels (3rd and 4th) with classes that don't advance them. If you sold me on it, I might let you count as still full progression because at 1st and 2nd level you took two classes that would advance it. You could not exceed the limit of your character level, e.g. if at level 8 you went Fighter/Rogue then you would only have level 8 Grace etc., but I would let you essentially "make up for" lost level progress.
Not all DMs will see eye to eye with me on that one, so definitely make sure to confer with your DM first.