"אחר שלוחיה" – Who Sent What to Whom?

Introduction

Shemot 18:2 states:

Yitro, Moshe's father-in-law, took Zipporah, Moshe's wife, achar shiluchehah.

This brief verse raises several related questions: What does shiluchehah (שִׁלּוּחֶיהָ) mean? Is it connected to the verb שלח (to send) which appears hundreds of times in Tanakh, or is it related to the noun שִׁלּוּחִים (a dowry or gift) which appears in only two other verses – see שלח and שלוחים. Is Zipporah the person doing the sending or is she what is being sent? Finally, when and why did this event occur (what is the meaning of אַחַר), and why did the Torah not mention it until now?