There are 10 μl of dual index in each well with some overage to account for storage and automated workflows.
The level of index hopping will not change with IDT for Illumina UD Indexes, but the index hopped reads can be removed bioinformatically from the demultiplexed data.
We have tested up to 6 freeze/thaws of frozen index adapters without observing any loss of activity.
There is no need to dilute the indexes before using them.
Libraries with the IDT for Illumina DNA UD Indexes will migrate similarly as prepped with CD Indexes which can be seen in their respective guides.