On
https://ethgasstation.info/ , the standard transaction cost seems $0.218 right now. What is this standard? How much raw data (in bytes) can it be carried per transaction at this cost?
This is the maximal cost for the standard gas limit of 21000 (typically used for a standard ETH transaction). You can adjust this with the "Gas-Time-Price Estimator" on this site.
I am not sure how many bytes a standard transaction need.