Is the Dock-It™ sufficient to hold the bag on the bike by itself? Although the Dock-It™ is an decisively strong connector, decaleurs are intended primarily as stabilizers and should not be expected to be the sole means of keeping the bag fixed to the rack. There are countless bag-to-rack attachments methods--find the one that works for your arrangement to work in conjunction with your Dock-It™ kit.
Can I braze right onto the Dock-It™ spindle? No. You will damage the internal mechanism and render your Dock-It™ unusable. Please refer to the complete installation instructions for proper bonding to either the B2B kit or a custom configuration.
What's the key that came in my Dock-It™ Kit for? The small aluminum key that came in your kit is meant for holding the Dock-It™ button in place when tightening the bolt to the button through the bag and/or other support structure. See the photo to get an idea. Without the key you'd need to grip the button with a wrench would chew up the smooth finish. At least one Dock-It™ owner has found the key to make an excellent keychain fob.
Remind me what the various parts are called: Sure--see below