Is there a grammatical reason for "spiser" to come before "vi" in this instance?
Because the verb always has to come in the second position. And the first position is already taken by "om sommeren". So 'vi' has to come after.
Sorry, 2nd position relative to what? Does Norsk then not follow a fixed S-O-V structure?
Norwegian would often follow a S-V-O pattern, but not always. The only thing that is certain is that in indicative mood, the verb will be in the second position. In this sentence, the time adverbial 'om sommeren' is first, so 'spiser' is second. After the verb, the subject should come in such sentences.
I think I understand that. I may need more clarification in the future so I apologize in advance!
There is absolutely nothing to apologize for :) learning a new language requires you to think in new ways, and asking for help to understand is important.
Which word order is more natural if you don't want to stress anything:
"Om sommeren spiser vi jordbær."
"Vi spiser jordbær om sommeren."
(I've seen the second word order in another sentence, but I think changing the order around would work here too, doesn't it?)
correct the crucial differences in the english translations of "om sommeren" and "i sommeren".
Firstly, you can't say "i sommeren". You can say "i sommer", which is a little hard to translate, but you can say it means "in summer" (implied this summer).
I think of "Om sommeren" is more general, and "I sommer" is more specific. I'll give you some examples:
"Om sommeren spiser jeg is" (In the summer I eat ice cream) "Om sommeren er det varmt" (In the summer it is warm) "Vi pleier å være på hytta om sommeren" (We are usually on our cabin in the summer"
"I sommer skal jeg til Polen" (In summer I'm going to Poland) "Lisa kommer hit i sommer" (Lisa is coming here in summer) "Hva skal du i sommer?" (What are you doing in summer?"
Hope this made it easier to understand!