Batch inscribing root inscriptions (multiple inscriptions in a single transaction)

[papiro]

I have a few questions:

I see when using the batch functionality that multiple inscriptions are able to be added in a single transaction. Is there a way to do the same but given no parent?

What is the limit to how many inscriptions (or total bytes) can fit in a transaction?

Is there a cost saving to packing a bunch of inscriptions in a single transaction rather than looping and inscribing (creating a new transaction per)?