Celtic names popular with early Germanic leaders?

I noticed that the leader of the German tribes under Spartacus
was named Crixus, which seems to be a Celtic name. Yet the Germans
seem to have been distinguished from the Celts who were with
Spartacus' army. Also, Ariovistus is (from what I've been told) is
a Celtic name, and he was a German king who fought Caesar. Also,
the Cimbri and Teutones' chiefs had Celtic names, yet they were
mentioned as being Germanic and their speech was said by Plutarch to
have been like none the Romans had ever heard (thus not Celtic?).

Thus, there seems to be a few possibilities:

1. In these early periods it was a common trend among German chiefs
and nobles to have Celtic names.

2. Many of these early German groups, such as the Cimbri and
Teutones, and the Germans with Spartacus, were a mixed Germanic-
Celtic speaking bunch.

3. These early Germans (up until Caesar) were Celtic speakers who
lived east of the Rhine (along with actual Germanic speakers) and so
were not different from the Celts/Gauls linguistically, but
geographically and to an extent culturally a lot like the actuall
Germanic-speakers and somewhat different than the Gauls/west-of-the
Rhine Celts. But can a Celtic-speaking presence east of the Rhine
at any period be substantiated?

Thoughts?
-Michael