Salvador is Spanish/Castillian. It means "Savior". There is a recent ugly copy of an old Church in downtown Moscow: Христа Спасителя. And a number of churches and towers - and a surname - Спасский. No personal name, though. Sorry!
Yuri
Клиффорд. Pretty much a direct translation of the name.
Douwg
Matvey
Бріттні Brittni
Морин Morin
The Russian language equivalent of the name Dmitry is Dmitriy (Дмитрий).
Juana = Ivana (Ивана)
Чарльз (Charl'ze) is how you would spell the name in Russian, if that's what you mean.
Jonny, Johnny
The Russian language equivalent of the name Mark is Марк (pronounced "mark").
The Russian equivalent of the name Michelle is Мишель (Mishel).
No. It is Russian for George.