First of all STOP doing his homework for him. He needs to be doing the research. If all he can find is in German, print it and send that to the teacher. Or you could have even asked here since some of us I am sure are fluent in other languages. I am fluent in German. Plus you have Babblefish and other translation programs available online.
Eight pages of research questions are not unreasonable for a 3rd grader. I've done those and normally there is space to write the answers under the question so it is not solid questions. Three days is unreasonable unless over a weekend perhaps and the teacher needs to extend the time for the assignment. How many actual questions were there. I can usually get 3 maybe 4 per page.
As to sending home graded papers, many teachers don't do that. Most have folders of each students work and will send it home at the end of each semester. You can set up an appointment and go in to look at your child's folder.
Spelling test postponed. It happens. Things that are not foreseen that change the schedule for the day and things have to slide at times. This is especially true if spelling test day lands on a day with a lot of specials. Throw in a fire drill and oops, spelling test is postponed. Have a program at the last minute and oops spelling test postponed. Have to go to an IEP mtg and again spelling test must be postponed.