Hi Cortney. Yes, some reviews are certainly easily discounted due to some of the remarks made by the writers, and how they're made.
As to your questions, I'll help as best I can, but will need to leave some up to those who have been onboard N. Gem.
Dining - I was told several years ago by an NCL maitre d' that the best times for going to the dining rooms are before 6:00 or after 8:30. I tried this myself on the little Norwegian Majesty several times, and it worked! As you are an early diner (as am I), this may be useful to you, too. So, even if you make a reservation, the earlier times may be easier to get and you won't have to wake up at dawn to make a phone call. Actually, the one issue I have heard about dining on N. Gem and her sisters is that the Teppanyaki Room fills up quickly due to its limited capacity and that seating isn't continuous.
Nickel-and-diming happens on almost every line these days. I spent a small fortune on tea on our Celebrity cruise this past summer. In many cases, coffee/tea are complimentary in the dining rooms and buffets, but not necessarily so in the small cafes.
Good questions -- some of our Gem veterans should be along soon with more specifics.