I portion out my bases to 300g and use freezer bags. When I defrost them, there is an awful lot of water coming out of the bags. I usually leave them out on a large dinner plate for a couple of hours to defrost. Should I discard the water or mix it back into the base?

I wouldnt to be honest.. not if its liquid from inside.

Personally I dont like that kind of defrosting... too much potential for bacteria to take foot. I put them in a pot of water and turn the heat on enough for the water to defrost them.

I freeze my base too, in 450ml portions.

The water will have separated on defrost, best stir it back in, since it came from the base in the first place, otherwise your base will have become more concentrated.

During the initial freezing, the growing ice crystals tend to 'reject' the solid ingredients, but its only on defrosting that this becomes apparent!

After defrosting, I bring my ex-frozen bases back to simmering temperature (in micro wave) and ensure it is hot and well mixed before adding it to the spices.

SnS

I just get mine thawed through and as hot as I can hold comfortably. It's usually 3 mins on half temp, stir, 3 mins on half temp, stir. This is for my 500 ml portions.