I like this mod! When playing on large automation-based packs, it gives new, interesting ways of working with smeltery.

Big modpacks have big variants of coolant items and liquids. It would be cool, if config have options to add custom entries with properties, like:

    S:"Coolants" <
        mod:material:5;1,8,1,1
     >

Issue #1 and it's a suggestion, woohoo! Can you give some use cases / examples? Not sure if I follow what you mean here.

For example, current list of parameters for Iceballs/snowballs have up to 4 parameters. They all can be moved to table together. But if there whould be ability to determine mod:id:meta of items, everyone can add their own items that valid as coolant

    # Mod:id:meta ; AmountBasin ; AmountCasting ; BasinAmount ; CastingAmount
    S:"Coolants" <
        minecraft:snowball:0;1;1;8;1
        mctsmelteryio:iceball:0;1;8;1;1
     >

Btw, it would be nice, if coolant items would have only 1 or 2 parameters - cast efficiency and basin efficiency, or just plain efficiency.
For example, snowballs would have efficiency 1 that means 1 ball can cast 1 item, and 8 balls can cast block. If iceballs would have efficiency 8 - they can cast 8 items and 1 block respectively.
If i would add my special item snow nugget and set efficiency to 0.5, it would take 2 "nuggets" for 1 item and 16 for block.

That is what I thought you were leaning toward. Thanks for the clarification. I will think on it and how to implement it.