I've had great success using 2.5% salinity for most batches. My understanding is that 2% is about the bottom range of what’s safe. You might try salting til it tastes good, figuring out what percentage that is, and try a ferment at that salinity. If it doesn't work you’ll know.

2% by weight (not volume) will work just fine.

2% should be fine, just make sure to include the weight of the water.