Familiar, yes. You have to throw the 1 level mage spell Find Familiar in order to conjure one (from book or from scroll). Your alignement will decide which one you get (see spell).
As for the strongholds, I'm not absolutely sure. I believe the stronghold depends on which quest you choose to do first. There might be a possibility to get them both if you're dualclass rather then multiclass. But I'm certain you'll find plenty of information if you use the search function for "multiple strongholds".
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Originally you can have only one stronghold - if you play without proper Kevin's patch then you can have two or even three strongholds depending on your class.
So sayeh
Wise Manveru Telcontar, The Mighty Wizard from Eregion