Studio work with NEX 7

I've gotten a basic studio portrait kit. Few umbrellas, stand, brackets, and so forth. I'm using Speedlights as my light source. Trouble is, trying to get focus fix and enough light to meter the subject. without constant nlighting, my lcd and evf are almost black. Can't up the iso to see thru the evf or the lcd because shots become extremely overblown. I realize if it was daylight there would enough ambient light to focus. How do you studio photographers, NEX cameras or otherwise, accomplish this at night in a studio? Should I placve more lighting in the room as general lighting?? My apologies for sounding or being so uninformed, but this is new to me. Any non judgmental help would be greatly appreciated. Thank you

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Sony NEX 7, Sony A550