What class to start with ?

[Radical Redemption]

Also without D3 Reaper of Souls untill what lvl I can play and which classes are not avaiable for me ?

Reaper of souls only gives Necromancer class and some cosmetic stuff.

[Svpernova09]

Reaper of souls only gives Necromancer class and some cosmetic stuff.

As stated, this is *not* true. Reaper of Souls is the expansion and adds another act and opens more rifts maps. AFAIK the Necromancer is *not* included and is an extra paid DLC/addon.

You may not have access to the Crusader class without Reaper of Souls. If not I would start with Barbarian if you like Melee or Witch Doctor if you like pet/ranged.