Devils fan here coming in peace. The 200s, while steep, are quite close to the ice and still provide adequate views in my opinion, certainly better than the 300s at the Coliseum in my opinion (and that annoying obstructed view). The 100s are worth the extra cost if they are center ice. You are really close because of the way the Rock is constructed and it creates a more electric atmosphere. The end-side 100s have a worse view for watching the game than the 200s.
As far as parking goes, it exists in decent quantities at private lots right across the street from the arena, but usually costs $20 a game. The team-owned garage is generally only for season-ticket holders. I suggest unless traveling in a large group to take NJ Transit or PATH. NJ Transit is easy if you are transferring from the LIRR (same station). PATH is dirt-cheap and a great option if coming from the city. Both stop at Newark Penn Station about 3 blocks from the arena. Taking public transportation allows you to get hammered safely before/at/after the game as well if that is your thing...
I had a great time on Jan. 19th at the Coliseum for the opener. You Islanders fans are a cheery and knowledgeable bunch. Looking forward to seeing you guys at the Rock on Thursday!