The Launcher for Elder Scrolls Online lives in its own folder. By default this folder will be:
C:\Program Files\Zenimax Online\Launcher
or (if using 64 bit Windows)
C:\Program Files (x86)\Zenimax Online\Launcher
Since you're able to customise the installation location of the launcher, this path may be different for you - if this is the case, you can find where the launcher is installed on your machine by searching your computer for Bethesda.net_Launcher.exe.
All of the downloaded launcher data will be stored here if you wish to remove it, along with the uninstaller for the launcher.
Both Vampires and Werewolves (PvE) will spawn in high-level areas, and their attacks have some chance of infecting you with the relevant disease. Once infected, you will have a new quest that you must complete to either become the monster you wish to be, or be cured of the disease.
You can not be infected by the Vampire disease if you are currently infected with the Werewolf one, and vice versa.
Vampirism Effects (more details)
You'll unlock a new skill line you can make use of, you'll also start to have these effects at various stages, until you feed on a human opponent (PC or NPC), which will reset it to "stage 0".
- Up to 30 mins:
- 30 to 60 mins:
- -25% Health Regeneration
- +50% Fire Damage Weakness
- -20% Health Cost to Vampirism Skills
- 60 to 90 mins:
- -50% Health Regeneration
- +50% Fire Damage Weakness
- -40% Health Cost to Vampirism Skills
- More than 90 mins:
- -75% Health Regeneration
- +50% Fire Damage Weakness
- -60% Health Cost to Vampirism Skills
Werewolf Effects (more details)
You gain access to a skill, Werewolf Transformation that does pretty much what it says on the tin. While transformed, you'll have access to a new line of skills to unleash your inner puppy, and there are some ill effects of course -- such as a passive ability that increases damage taken from abilities in Fighters Guild skill line, +50% to all poison damage.
PvP Infection
Players can also infect other players with their condition.
For Werewolves, the skill Bloodmoon can be used once every seven days, acting as a rate-limit. For Vampires, the equivalent skill is called Blood Ritual. You have to use these skills at the ritual sites, so it's unlikely you could be turned against your will. Both require level 6 in the respective skill trees.
Best Answer
Only for vampirism:
For vampires: "As a result of the hemophiliac virus, the infected slowly grow paler. Fangs protrude from their gums, allowing for easier feeding for blood. Eye color changes from the spectrum of average hues to red. When infected, the fur of the Khajiit alters as the skin of a human or elf would. Long-toothed by nature, the incisors of the Khajiit grow exceptionally long, so that they protrude below the lip. However, their pupils become thinner and more blade-like. The scales of Argonians grows greyer as the infection worsens."
For werewolves you don't change appearance unless of course you transform into a werewolf, and if you do you also have to kill to stay that way.
Vampirism in Skyrim (the visual papearance is almost identical)
More on Lycanthropy