Merfolk and burn aren't the easiest matchups. That's a bad break. Did you feel like the deck just didn't play well that night or there were cards you'd consider cutting/adding? I personally am a big fan of burst lightning particularly for matchups like burn and merfolk.
Goyf is good in the blue mirrors, but I think you find situations where it becomes awkward to play moon turn 3 while still being able to cast goyf turn 2 and crytpic turn 4 or beyond.
I really liked burst lightning. It kills early threats at instant speed, and you can't discount games where you kick it end of turn to turn the tide of a race situation.
2 Vandalblast
1 Keranos, God of Storms
1 Roast
1 Harvest Pyre
2 Dispel
1 Negate
2 Anger of the Gods
1 Batterskull
1 Molten Rain
1 Jace, Architect of Thought
1 Izzet Staticaster
1 Relic of Progenitus
Not the hottest finish, but I felt like the deck played really well. Faced the eldrazi menace 5 times, giving me 3 of my losses. Vedalken Shackles was the mvp for me.
I keep reading about allowing the meta time to adjust. I think that's a great general philosophy, but looking objectively at those lists, I don't see very many realistic opportunities for combatting the deck that don't neuter your own. When creatures like tarmogoyf and vendilion clique are outclassed by creatures that can come into play just as quickly, we have a problem. Their mana situation allows them to outclass other creatures in a largely creature-based format. Nobody should have to run painter's servant to deal with this degenerate deck.
The advantage of playing multiple decks is that you get an understanding of how various decks/archetypes work which will help you when you face them. It's also more fun if you play a lot of fnm sized events to not have to play the same thing every week. That being said, if you're focused on larger tournaments, it might make sense to practice one or two decks, so that you get a stronger handle on them. In terms of acquiring cards, get staples and then you'll be able to easily switch between decks. I've played a lot of different decks, but when a tournie comes around, I always sleeve up a ur/x deck because I feel most comfortable with that. Being 16, you've got a ton of time to play and build a collection.
I'm personally happy that they even reprinted the onslaught fetchlands. It means that new modern players could at least participate in the format albeit with non-optimal mana bases.
4 snapcaster mage
2 Pia and Kiran Naalar
1 Wurmcoil Engine
3 Mana Leak
4 Remand
4 Serum Visions
2 Spell Snare
2 Cryptic Command
4 Lightning Bolt
2 Electrolyze
2 Burst Lightning
1 Roast
1 Batterskull
4 Blood Moon
2 Vedalken Shackles
8 Island
2 Steam Vents
2 Sulfur Falls
4 Scalding Tarn
4 Polluted Delta
1 Mountain
1 Desolate Lighthouse
Sideboard
2 Vandalblast
1 Keranos, God of Storms
1 Roast
1 Harvest Pyre
2 Dispel
1 Negate
2 Anger of the Gods
1 Batterskull
1 Molten Rain
1 Jace, Architect of Thought
1 Izzet Staticaster
1 Relic of Progenitus
Not the hottest finish, but I felt like the deck played really well. Faced the eldrazi menace 5 times, giving me 3 of my losses. Vedalken Shackles was the mvp for me.