Wow, thanks for all the questions!
First off, a general disclaimer - Quakers are a disparate group; one of our defining characteristics is the lack of formal tenets. As such, unless I specify otherwise I am talking about my personal beliefs and experiences, and another Quaker may disagree.
Starrsmother - First off, I am a Christian. I believe that my own behavior is unworthy of God, and am dependent on his grace for salvation. What defines me as a Quaker would be my not holding to physical sacraments and symbols, which I believe have at times have become a distraction from the important concepts which they represent.
Bergon - Traditionally, Quakers used their own nomenclature for a number of familiar Christian objects - ie, “meeting house” instead of “church”. The original intent was to reclaim the focus on the underlying concept rather than the object - the church was where the congregation was, not the building itself. This practice of using distinct speech has become less common, largely because this different manner of speaking actually became itself a distraction from what was important. In my local community’s parlance, the building is referred to as our church and the group of people that meet in it are the congregation, meeting, or church group.
Sitting is silence is an important tradition, and some meetings still have services that are either fully silent or are unprogrammed (where there is no pastor and members of the congregation speak as they feel led). My church is more conventional - unprogrammed worship takes up less than 25% of our typical service, and we have a pastor who give a sermon.
dawid - Quakerism (formally “Religious Society of Friends”) started in England, in the 1600’s IIRC. A man named George Fox was dissatisfied with his religious experience in the Church of England, and felt the answers he received to his concerns were unsatisfactory. He founded Quakerism as a separate denomination, and as a group early Quakers did little to avoid standing out starkly from more established religious groups. As a result, there was significant persecution of Quakers in England and later in New England by Puritans. Pennsylvania was essentially a Quaker colony in early to mid American history.
Discerning, adawgj - according to Wikipedia the founder of Quaker Oats just used the name because it sounded wholesome (I had to look it up). Pepsi owns the brand now.
I will try to address the other questions later, thanks!