Hi @stremglav,
My sincere apologies, but it looks like you have some old documentation there. For a new integration, we'd recommend starting with the current eCheck documentation and the eCheck specific sections of our API Reference guide.
If you already have an existing integration using our older API (with the "x_" fields), then you might find the PDF helpful for just adding eCheck functionality. But, for anything new, we'd always recommend you start with our current API.
To answer your specific questions, eCheck authorization is not instantaneous, however, you will get a response to your request right away. You need to know immediately whether we received the request and whether there was any obvious problem with the request, so we give you an immediate response to let you know. If that response indicates that the request is successful, that's not a guarantee of funds; it just means that your transaction will be submitted to the customer's bank for funding.
For the fields, it may be possible in some cases to get the transaction to process with only some fields. However, you may find that one bank may have stricter requirements than another, so we suggest providing all of the information for the transaction. In that sense, all of the fields listed would be required for optimal transaction processing in production.
