I just want the same behavior as the Space Age, but with all intermediate recipes

Use default settings, change both "Minimum required science pack" and "Maximum required science pack" to "One Planetary Science" and remove the checkmark in "Adjust existing productivity technologies to follow the same progression?".

Can I update the mod or change settings on an existing save?

Usually, you can update or change settings on an existing save. The exception is if you're currently researching one of the technologies this pack adds or modifies maximum level and have already researched more levels. In both cases I have no idea what will happen. :)

I encountered an error/I have a suggestion or new idea/Can you add compatibility to X?

Feel free to open a thread on the mod portal or an issue on github. Please include a list of active mods (or your mod-list.json) and settings if they differ from default.

I try to fix bugs and add optional dependencies as quickly as possible. If it's a major idea or full compatibility with a mod that usually requires more time.