Lindsay, we do not have perfective/imperfective verbs in English so your examples with see and seeing are not correct. We do have the perfect tense (present and past as in I have seen, I had seen). These are missing in russian and give them as much grief as perf/imperf give us.
Perfective focuses on the RESULT of the action, imp. focuses on the action itself.

Я буду читать газету завтра. I will read the newspaper tomorrow.
Я прочту газету завтра. I'll get the newspaper read tomorrow. I'll read it through.
Вы будете делать это завтра. You'll do it tomorrow.
Вы сделаете это завтра. You'll get it done tomorrow.

Я ездил в Москву. I went to Moscow.
Я ехал в Москву. I went to Moscow.
In the first, the focus is on travel, so the verb may or may not have been repeated. Usually means round trip, even with a prefix as in Они съездили в Москву. (but motion verbs is another can of worms!) I don't even know whether you can say Они съехали в Москву. Кто-нибудь не подскажет?

In the second, the focus is on the result, I went, and I am still there.