You can play as a dragon Burning Skies - Flyable Dragon Races 3 mod by ElSte17 and UbuntuFreakDragon on the Skyrim Nexus.
If you just want to fly, you can ride dragons in the Dragonborn DLC.
You cannot fly AS a dragon, but you can fly ON a dragon in Skyrim. Near the end of the main quest line, you must call and capture Ohdaviing, Alduin's right hand man, to help you defeat the World Eater. After chatting with him for a while, you can trust him to take you to Alduin's portal to Sovngarde. The only way to get there is on dragonback, and you see your character mounting him and flying off to the northwest.
a necklaces, you can only have one on at a time
No. Dragonborn needs Skyrim to run
sadly, no
The only ridable dragon appears at the end of the main quest mission 'The Fallen', and it is not any kind of steed, it simply does a cutscene to take you to a different area.
If you download the 'dragonborn' DLC, partway through the storyline you will gain a shout to enable you to fly dragons.
NO...
Red dragons do not exist in Skyrim. There are green, brown, bronze, white, and the end game boss Black dragon.
A dragon found at the Throat of the World in Skyrim.
You cannot fly dragons without either DLC or a mod. However, with the mod "Fully Flying Dragons" by gg77, you can fly dragons without DLC if you use version 4.3. You can find this mod on Nexus Mods.
The closest you get is a shout which can summon a dragon who has allied with you, this happens during the main quest.
There is no Dragon Priest Armor, only their masks.