As far as I know, fire rate and reload speed do not affect medic, so berzerker wouldn't either.
The main thing you need to worry about with a medic loadout is getting the three main medic tools from worth menu: Medkit, Medic Pistol, and Medic AR. You rotate between those three things when healing people. Also, on wave 1 intermission, you should buy a deagle which crafts with the medic pistol and an ender shotgun which crafts with the medic AR. The cooldowns on those crafts are faster than their original weapons, so you can heal faster.
Also, buying medic grenade from the supply crates is very useful.
Example loadout, forgot to write down medkit when I made it but please don't forget to buy medkit. You can mess around with the loadout and get more returns in exchange for other traits. Sometimes I like to fit repair traits in and help repair the cade when no one is hurt.