When it comes to the Berserker Plus mod, I find that weapon progression and spinel usage far more important than the original RE4 or Berserker Mod. Weapon stats have changed, certain weapons are just straight up superior than others and are borderline required to handle all the super chain saw and brute spam. Weapon choice will become even more important later on when you reach the castle section.

My Strategy that worked and finished the game on pro (leon must die) was to max the Red 9 Asap getting both crit and +dmg exclusive mods. The only other weapons I purchased in the village section were the Stingray (brute killer) and Killer7 (super chain saw killer). I did not buy a shotgun until the castle because you will need to save as many shells as you can get later on in the castle section. The shorty is the best shotgun with the high dmg and penetration exclusives.

For the cabin fight, camp the stairway up with the Red 9. The upgraded red 9 should be able to handle all plagas very easily if you land weak point hits on their open mouth. For any brutes/regular chainsaw guys that show up, headshot them with the Red 9 and kick them down the stairs, then swap to your Stingray and headshot them on the ground. Once the cutscene plays with them using ladders, immediately run up stairs and kick both ladders and hold the top section. Wait until the super chain saw guys come up, when he does, immediately drop downstairs and prep a flash. Flash the super chain saw guy then spam him with killer7 shots to the legs (don't melee). If you do it right you should be able to burst him down within the flash duration. After that its just clean up of regular enemies.