iATS Extension Working, but Throwing Errors
To suppress notices/warnings on Drupal go here:
/admin/config/development/logging

and hit: none
(you'll want 'none' on any production site);

Would you please open up on issue in our GitHub queue:
https://github.com/iATSPayments/com.iatspayments.civicrm

paste in your notices - and also let us know exactly what type of transaction you're executing when these notices occur? Frontend/backend; Credit Card; ACHEFT; SWIPE; one-time/recurring; Contribution; Membership or Event etc.