Yes, "expect" could mean "believe that (someone or something) will arrive soon." We can rewrite the sentence "The things are believed to arrive soon; The things help us." Therefore, "the things" equals to "they".
Colonization hundreds of years ago is held accountable for such situation. (incorrect)
Colonization hundreds of years ago is held accountable for such a situation. (a specific situation)
Colonization hundreds of years ago is held accountable for such situations. (all of a number of such situations)
Colonization taken place hundreds of years ago is held ...
Adjectives and Adverbs
To tell apart adjectives and adverbs, "the adverb questions" are a handy tool. Asking the right ones helps you identify the adverbs in a sentence.
Sam freed up the clog with a plunger.
How did Sam free up the clog?
With a plunger.
Max barely studies.
To what extent does Max study?
I take it that someone has told you there is an error. My first idea is that they want you to put the article "a" before situation. Some might think it unnecessary, but as an American speaker I think you want it - unless you are talking about the location that a colony literally is situated in. Even then, just to avoid someone interpreting ...
I don't really understand what you are saying; "hundreds of years ago" is not an adverb. "Colonization hundreds of years ago" is perfectly correct.
Your "better alternative" is in fact worse; you would need to say something like "Colonization, which took place hundreds of years ago, is ...".
However there is a problem ...
As a native speaker but not a grammarian, the original sentence is fine. Your version also makes sense but the that is unnecessary making the original slightly preferable.
The comparison is between the grain ration in rural areas and the grain ration in cities. By not mentioning grain ration again or that, it is implicit that the same item is being ...
The word "for" is used for duration. For instance, "I was in Hong Kong for three months". It's not appropriate for counting the number of instances, rather the duration of instances. "The baseball player has pitched for 42 games in a row" can be seen as grammatically correct if "42 games" is viewed as a length of time, ...