1. During the Dawnguard DLC, you recieve a quest to turn someone into a vampire, who you previously has turned into a vampire.
2. Your wife/husband cannot be turned in the Dawnguard.
3. I cannot summon the Dragon from the netherworld in Dawnguard.

Dragonborn

I have visited Dark Elf Island and taken 5 of 7 books. I have later returned and taken book 6 in the temple of Miraak. Then you recieve a quest in which you should visit the Dark Elf wizard. As soon as he sees me, he immediatly launches attacks.

Skyrim

I've been to the Greybeards and started to locate Shouts, and suddenly I got a mission to locate a Shout in the south. When I've defeated the dragon, and should take the voice it would'nt start giving it to me.

I have Lvl 57, so I really look forward to some solutions for my XBOX.

Well, those sound mostly like glitches, but the dragon summoning one I can help with.

Make sure you use all 3 words, and you look at the ground in a place big enough for him to fit when shouting