A: Yes. Mercenaries high scores are saved to the same memory card but are unlocked globally. If you download a save with 5 stars on all characters, you can play Mercenaries immediately without beating the story.
Understanding where your progress is stored is the first step in managing your game. Virtual Memory Cards: AetherSX2 uses virtual memory card files (typically with a extension) to store in-game saves. File Location: On most Android devices, you can find these files in the Android/data/com.tahlreth.aethersx2.alt/files/memcards Save Data Resident Evil 4 Aether Sx2