Its appearance would suit the Volkihar clan though since they are not supposed to blend in, i suppose it could be tweaked but i find the appearance quite vampiric, its like a demonic bat although the wings don't suit it.
A Vampire version of the Frost/freezing breath should have been added since all one has to do is recycle the current one which is a dragon shout and tweak it and add vampiric drain to it.
You don't need to join the Volkihar clan since that is the type of vampire you become once infected but i agree that one should be able to join a faction of vampires.
Actually, i believe there are two seperate Vampirism strains in Skyrim. The "Sanguinare" is what the player can become, and they're more of the "Order" type. Then of course there's the Volkihar.
I posted an idea for a mod awhile back that listed the bonuses and negatives of having the "Volkihar Vampiris" strain, and the powers fit with the lore.
Baseline, the "Volkihar Vampiris" strain would have 100% Disease and Poison Resist, 50% increased damage/duration for Frost Breath/Ice Form shouts (Similar to "The Fire Within" from Paarthurnax) , 25% increased damage with Frost spells (Similar to the "Augmented Frost" perk), Water Breathing, and have Frost Resist. However, the "Volkihar Vampiris" strain is Weak to Fire, would actually cause you to take damage and burn in the sun at any Lvl of Vampirism (Which can be cut to 1/4 damage when wearing full robes with hood), and NPCs would almost always have a negative reaction to the PC. Guards will attack you on sight, while alot of "civilian" NPCs recieve a lowered disposition with you, and some are terrified of you (These can be overcome with Calm spells). However, you recieve a bonus to "Intimidation" checks during dialogue (Similar to the "Intimidation" perk in Speech). "Volkihar Vampiris" PCs are able to feed in combat through Vampire specific finishers, and become more powerful the more they feed. Every 3 NPCs killed with the "Feed Finisher" increase your Vampirism Level by 1, up to Lvl 4. You lose 1 Lvl of Vampirism for every 12 Hours you go without feeding.
At Lvl 1 Vampirism, you have 25% Resist Frost, 50% Weakness to Fire, the "Vampiric Drain" spell (Revamped for better mana-damage efficiency for both strains), a "Vampire Sight" Lesser Power, and the "Icy Touch" Greater Power that deals 25 Frost Damage while Paralyzing for 3 seconds.
At Lvl 2 Vampirism, you have 50% Resist Frost, 75% Weakness to Fire, an improved "Vampiric Drain" spell, +25% Health and Stamina Regeneration, and the "Fear Aura" Greater Power that functions like a "Cloak" spell for 120 seconds that causes all enemies 5+ levels below you to cower or run in terror from you for 30 seconds.
At Lvl 3 Vampirism, you have 75% Resist Frost, 100% Weakness to Fire, a further improved "Vampiric Drain" spell, -25% Damage Taken from Iron/Steel Weapons, and the "Icewalker" Power with a 5 minute cooldown, which allows you to create a solid Wall of Ice in front of you which enemies/arrows/spells cannot pass through, but you can. It lasts for 30 seconds.
At Lvl 4 Vampirism, you have 100% Resist Frost, 125% Weakness to Fire, a powerful "Vampiric Drain" spell, +35% Weapon Damage and the "Frost Spit" Power with a 3 minute cooldown, that "vomits" forth a freezing liquid that deals 10 Frost Damage per second for 5 seconds (Similar to the "Vomit" ability of the Afflicted), and sticks to the ground for 10 seconds, acting similar to a "Wall of Frost", dealing 10 Frost Damage per second that the enemy remains in it.