The difference in meaning is subtle, and it may be too subtle to matter in many instances. However, this lesson is on the preteríto perfecto, so DL wants the English in the present perfect.
"This week I have eaten much" is marked as in correct, when it should be correct. "This week I have eaten too much" which may be acceptable, but would be more correct if the Spanish had been "...demasiado mucho"
IMHO I don't think that you would need "mucho" after "demasiado" since "demasiado" translates as "too MUCH."
Agree, but DL said it should be singular. I feel "lots" and "a lot" are no different in this context.
You would never say "tengo comido mucho". Tener means "to have" as in "to possess", it would not be used as part of a "perfect tense" (I have/had/will have/would have .... e.g. I have played, I would have eaten, I had slept, etc...)
Can anyone give me this in a normal English context? I don't really understand why we would ever need to say this at any point at all.