גר ומסתעפיו

Was wondering about the connection of the various points:

1. Ger גר as in convert
2. Ger as in settler גר ותושב
3. גרה as in גרה לא יגר - regurgitation
4. גרה as in עשרים גרה יהיה השקל
5. הגר שפחת שרה
6. גרמא וגרם ??
7. לשון משנה גרגיר ענבים
8. גירוי - instigation and conflict [note the french "guerre" = war/conflict , as well]

Was thinking along the lines of movement/change/wandering... but not completely satisfied by it's usage in #1 i.e. a regular Ger. His conversion to Judaism is pretty final so how would that justify a word that connotes constant change and movement.
I don't have #4 worked out exactly either but was thinking to connect it to the Gm' Bechorot 50a in the drashot of מוסיפין על השקל ואין פוחתין---
דתניא עשרים גרה השקל למדנו לשקל שהוא עשרים גרה ומנין שאם רצה להוסיף יוסיף ת"ל (ויקרא כז) יהיה יכול יפחות ת"ל במדבר יח) הוא
Problem is though that over there it's really the shekel that is changing not the unit of gera itself..... וצע"ע
Also interesting to note that the word is one of the א"ת ב"ש ג"ר.