See our septs page for an explanation and a list of septs for each branch. The name became whatever the immigration official thought it should be based on the way it sounded. It makes no difference at all. Go to the membership page, fill out the form, and mail it in with your dues.
Dues go to pay for newsletters, advertisements, and clan activities.
The clans, however, were overall a Highland institution. We encourage you to join in your local Celtic organizations and indeed, with clan organizations to help keep the culture and tradition alive. There are no pockets in a kilt. There's several different types, mostly concerned with how formal the attire and what time of day - fur with a silver top for formal evening, leather with no silver for casual daywear, etc. Scots Gaelic is spoken for all intents and purposes only in the Highlands and Islands - even then, only an estimated 70,000 people in Scotland speak Scots Gaelic.