Great post, many thanks for the info! There are 2 more ships that can be acquired for free.
1. USS Oklahoma, as reward for finishing the Always Courageous Collection.
2. Russian Battleship Oktyabrskaya Revolutsiya if you meet the following requirements:
- Play WOWS through the Steam Platform.
- Be a new player or have less than 8 battles in any combat mode.
- Finish 2 battles in tier III or higher.