Yes, but probably not with the DLC cars. You can edit a file associated with a car that ends with .rcd. But not sa ll cars/mods have them, and not all mods work even if they are included. You probably have to use the dev mod to extract the files, edit, and repack them.
Yes, it's possible, even with DLC cars. For example, let's say that you want to change AI names and define strength for McLaren 650S GT3. You need to unpack v2.61 (current latest version) of the rfcmp file. After unpacking, you'll get car-upgrade.mas file that also needs to be extracted (using MAS file utility). In order to change AI name, edit in .veh file line that starts with Driver= For strength edit, create .rcd file and first line has to have same entry as in classes in .veh file (set GT3 for McLaren), and then inside curly braces have an entry for each driver whose strength you want to define. So for example, you can create rcd file that looks like this. GT3 // same as class in .veh file { Andrew Watson // same as Driver in .veh file { Nationality = DateofBirth = Starts = 260 Poles = 8 Wins = 9 DriversChampionships = 1 Aggression = 75 Reputation = 85 Courtesy = 80 Composure = 90 Speed = 84 QualifySpeed = 84 WetSpeed = 80 StartSkill = 90 Crash = 1.1 Recovery = 93 CompletedLaps = 95 MinRacingSkill = 79 DrivingLine = FAST } } Then, you need to repack extracted mas file and create new pack for talent file and copy/install to rf2