Ret, disc is more or less dead because of Paladins burst not being high enough anymore and retris not having MS.
Ret, warlock, disc might work but it´s all about bursting at the same time when the disc gets a fear in on the other teams healer. I woulden´t recommend the setup though.
As for 5v5 sure but you should prolly take the mage instead of the rogue to get more spelldamage vs bop and having 3 meele isn´t that good vs diffrent aoe attacks.