Can you still get the stuff?
I've had to throw away a character I really liked just because I hate the dawnguard questline so much, he'll eternally be at the moondial looking for stupid half moons because I refuse to do that [censored].

The only reason I got dawnguard is I badly badly wanted the dragonbone warhammer. So if next playthrough the big orc approaches me with the letter about the vampire hunters and I'm just like "whatevs" and don't go do anything about it, will the options to craft dragonbone weapons still be there? Or better yet will there be a chance of finding a dragonbone warhammer anywhere else in the game? Will anything of the unique dawnguard content be present in the game despite not starting the quest?

Yeah if you've got the Dragon armor perk in smithing you can make it yourself it has nothing to do with the DG storyline.

Why did you throw the character away? I mean... why not just... leave the Castle and continue on with the game?

If you have your Smithing at 100, you can craft your own Dragonbone weapons.

How do you get rid of serana? The whole thing just soured me, it doesn't take much for me to start again, I've done it a million times. I haven't actually deleted his save file, I just started another one and don't feel like going back to him because of how gay the DG questline is.

Ugh. Really?

Oops, I meant ghey.

I personally liked the DG questline, and those moon dials aren't hard to find, they are all sitting right there in the courtyard...

Anyways, Yes if you decide not to start the DG questline you still have access to a few of its features (mainly Dragonbone weapons and Werewolf Perks),

however you will not have access to Crossbows, Vampire Lord form, any of the spells it added, etc.

Hmm thanks, I guess I will probably wander into the place to get the crossbow and turn around on characters I want to have a crossbow.

Really can't stand the quest, the moondials were just the last straw, I hated dragonborn as well but finished it. I'm really not into puzzles. In DB where you have to put the cube here and lower the water and blah blah blah, god I just can't stand that stuff. Obviously a bunch of people love it and have complained they need more which is why they've made the DLCs like that, but damn, it reminds of everything I hate about other games like Uncharted. As soon as some laborious task like that sets in motion I feel locked in, the very feeling I never want to feel in any video game.

those Dials aren't hard to find, they are all in that exact Courtyard, and there are only three. they stand out as well. Ones Leaning up against a wall, ones behind a Plant.

you don't have to go into any of the Surrounding doorways to find them, there are nothing really inside those doors anyways.

I'd complete its quest at least once, at the end you can tell Serena to bug off and never see her again (besides, Soul Cairn has amazing loot if you use Conjuration), and the Final Boss is fun as well.

you can get some really good rewards at the end. you can learn to make a Crossbow much more powerful then the one they give you. you can only craft Bolts for them at the Dawnguard Fort after you complete it. you can learn Spells that make slaying vampires extremely fun. you get one of the best looking armors in the game (ancient Falmer), and Auriels Bow can be very fun with Sunhallowed/Bloodcursed arrows.

Using either one as a slur or derogatory term will earn a warning. This is why it was in the autocensor at one point. It was taken out because posters seemed to have matured enough to not use it.

One of those moon plaques is in the puddle/water. The other is in plain sight leaning against a wall. Third one is behind a plant, as funnybunny said.

Leave DG installed and not finish the quests means vamps will make short work of the NPCs in the game.

Make sure you visit lots of shops so when the owner dies, you get an inheritance.