If you side with the Vampires, the Dawnguard will hunt you. That means, teams up to 3 people with at least one crossbow.
For the Dwemer-Crossbow, you have to make a quest for the Dawnguard to make a special character join, and then do a quest for her.
If you not side with the Vampires, from some point on, Serana will have the option to make you a vampire. (As long as you don't persuade her to let herself healed.)
What platform do you use? Creating a mod that let anyone create a Dwemer-Crossbow should be very easy, even for PS4.
Yes
And the dwemer-bolts are looted from the dwemer-automatrons, anyway.
... also, the Trolls as pets are Dawnguard-Exlcusive. But the vampires do have the Death-Hounds, so it is all what you like more.
Well if we're talking about items here that page is probably quite conclusive. Don't worry so much about it. There are cool things you can get as a vampire as well, like the aforementioned rings.
If you really want those items maybe you could ask for an ESP in the mods forum, to unlock them all.
Both sides have their unique quests and items.
But as told before, even if you side with the Dawnguard, it will become possible to be turned into a vampire-lord.
Playing Skyrim is fun! Just do each side one, that's double the fun of just playing one side.
Ah, but that will not just allow access to item-related quests, as they come after Harkon's offer.
Still, I don't see it as a huge loss.
Just a side note to the post just above. You can get the Heal Undead spell tome in the Dim Hollow Crypt dungeon. Doesn't matter which side you're on
That's Necromantic Healing spell (Apprentice lvl, heals 10 points/second, just like Healing hands spell).
Heal Undead is an Adept level spell that heals 75 points (just like Heal Other spell).
It is possible to buy the book from Ronthil, even if you sided with Dawnguard, if you use a glitch, but that's another story...
One of the rings is the single best enchanted item you can either find/buy or enchant, if you're a mage. You can get your vampirism cured later, if you don't want to be a vampire for the whole game.
As a side note about the Dawnguard Rune items... you can get every one of those items from Dawnguard patrol NPCs that wander around, and from the Dawnguard assassin groups that try to ambush you. If you have the mod Immersive Patrols, it adds many more Dawnguard patrols to the world and so those items are not hard to find at all. I found all three of those Rune items just yesterday, in the aftermath of a battle between a Dawnguard patrol and some bandits. With high stealth, it's also possible to sneak right into Fort Dawnguard yourself and lift those items off NPCs and take the ones that are lying around (I've done this on 90% sneak, light armor + muffle boots, AND I was a vampire! Just stay away from the husky dogs.. they'll bust you).