Local FNM varies greatly between play groups. Some are extremely competitive and focus entirely on quick kills, while others are more about having fun, and still others are all multiplayer instead of duels.
You need to discover what is normal for the FNM group you will be playing in. You can simply play at one and see how you fare, or you can go and watch. In either case, here are the things to look for:
Do players only play standard, or do they play pauper, or EDH, or something else? Do they rotate between different formats on different weeks? (Here is a good page to reference.)
How many turns do games normally last? Short games indicate aggressive players trying to win. If games last thirty turns, you're looking more at games just for fun. If it is all over the board, then you have tons of variations between different decks.
How many players are there? Large groups will mean more variation in who attends on any given week and what decks you face.
Once you know what to expect, you can design your deck(s) around what they are doing. If everybody there is just out to have fun, and you build a super-fast, kill-everybody-in-three-turns deck, then you will win a lot of games and no one (yourself included) will have much fun. If they have super fast decks and yours takes twenty turns, you will lose a lot of games and won't have much fun. If they play pauper every other week and you show up with a standard deck, they won't even let you play in the tournament (though some players may play a side game or two with you).
If they play a style you don't like (or can't afford), you can still make friends and play games outside of FNM.
Artifact/enchantment protection is perfect for a sideboard. If you expect most decks to play them, you include stuff like disenchant in the deck. Otherwise, you put four to six cards in your sideboard that help control them, and rotate them in if your particular opponent uses them.
Which is what a sideboard should be. Cards like Gainsay are usually too situational to be useful; unless there are a great deal of players using blue, and you often wish you could counter their spells because you can't handle them any other way, I wouldn't include it in a sideboard, and instead put in something else. As a rule of thumb, sideboards should help you deal with something your deck is weak against. Should you need more space in the sideboard, remove cards that are too situational. If you need more space, remove cards that do similar things to cards already in your deck, like Arrest.
Other thoughts... Dryad Militant is a good card against certain decks, but Soldier of the Pantheon is probably more useful against more decks. If you can afford it, put the Dryads into your sideboard and put in more Pantheons. If you face a deck using Revive or flashback cards, you can swap the Dryad back into the Pantheon's place. If you can't afford it (which I couldn't), then you probably want to take the Pantheon out and use that card slot for something else, perhaps Favored Hoplite or another 1-cost creature that fits your theme.
If your goal is to trigger Heroic, I don't think Fortify and Brave the Elements count, as they are global effects, not targeted ones. While those are both good cards, you may look for something to trigger Heroic abilities instead. Likewise, Soulmender isn't a bad drop, as it can give you some health or block or attack, making it versatile, but it isn't heroic.Elixir of Immortality seems a little out of place in this deck. If your format allows it, I would look at cards with storm or buyback, as they work well with heroic.
Your largest creature is 3/3. You may wish to put in two cards that are larger, like a 5/5 flier. Blue and White both have many creatures that fit the bill. These creatures can become a secondary win condition if you face an opponent who can deal with your ground creatures or your enchantments. They will of course require more mana to play, but having two in the deck means you are unlikely to draw them both early on before you reach the mana necessary, while still likely to draw one in a prolonged game. Putting in Gift of Orzhova can also help with this, and I see it is in your sideboard. I would consider swapping it into the main deck.
Let me give you some common terms and definitions to help you feel a bit more comfortable. You may already know some of these.
Mill decks focus on killing you by removing cards from your library. Sometimes this is direct (Balustrade Spy), and sometimes they just make you draw so many cards that you run out of cards to draw.
Discard decks force you to discard, and are a form of control deck. There are card combos that trigger when opponents discard (Confessor), but other discard decks force you to discard merely to keep you from playing cards.
Burn decks do direct damage to opponents or creatures. A burn deck contains many cards that perform a function similar to Lightning Bolt, and many burn decks contain cards that do damage to all creatures and/or all players (like Tremor).
Token decks are a more recent development, and focus on creating lots of expendable creatures (Acorn Harvest). These decks win by overwhelming their opponents or by making those tokens large with global buffs (Overrun)
Control decks attempt to control everything their opponent does. They counter spells, remove permanents, destroy lands, and/or bounce (Unsummon).
RDW means "Red Deck Wins," and is a common phrase because red decks can get overpowered.
Tribal decks focus around a specific creature subtype (Knight Exemplar). Common tribals are elves, knights, goblins, vampires, etc.
CMC, or MC, is converted mana cost or mana cost.
Boros is red and white. There are nicknames attached to almost any color combination. Why M:tG players create more terms to know is beyond me, but we are quite fond of our own little made-up language.
These are examples. There are many decks that are named for what they do. For example, life drain decks steal life from opponents and gain that much life, such as Corrupt, and reanimation decks continually bring creatures (or sometimes other spells) back from the graveyard. These will be fairly obvious to you over time as you become familiar with what is possible. Other decks are named for combos they use, like Juck Turtle's Legion of Invulnerability (named for its use of Assemble the Legion). You'll get to know the names of cards over time, though if you are like me you'll still frequently look up decks named after cards because there are simply so many cards and card combos.
Sorry this is so long. Hopefully it is useful information.