Marcus has been my primary caster. As far ad using him I have loved his totem. I think you have to have at least one moleman tunneling at armor 5 to be the target for "defend me". Also remember that combining feral with alpha lets you use an opposing model and stil perform another 0 action.
On Myranda she copies everything except spells but keeps her own. But animal instincts let's her cast their cost 1 spells. Like constrict, roar, uproot, and most importantly the jackelope's magical extension. Not to mention any cost one spell on any model Marcus puts feral on. I used Myranda to cast rasputina's ice pillars and December's curse.
As for what to run with Marcus I think Myranda is an auto include. The tiger is great. At least one moleman as stated earlier. And I converted a waldgeist which is nice.
As far as range.... I havn't had much issue but Hans and the convict gunsling caught my eye.