1)
~ということは means "judging from (a fact that)~" here.
2)
In the point that にとって is used, yes.
3)
Which に are you talking about?
Look up 熱心(な) in a dictionary.
4)
時 just means "time".
As for 過ごす[sugosu] and 過ぎる[sugiru], yes, they are a transitive-intransitive pair, as same as 起こす[okosu] - 起きる[okiru], 降ろす[orosu] - 降りる[oriru], 滅ぼす[horobosu] - 滅びる[horobiru].