No to all of the above, except on LinkedIn, i'll sometimes accept a request if it's someone in my industry that has connections with people I work with.
Speaking of cold calls, I've had the same recruiter call my work phone the last 3 weeks, probably at least 3 times a week, wanting to meet up with me, introduce herself, yadda yadda. First time she left a voicemail. Every other time I hit decline when the call comes up on my computer. She's not getting the hint, I've never answered and never called back. Give it up.