Do I send them a yellow letter or skip trace and cold call?

Yes, I skipped posts after the second, using any entity is still going to be a violation, don't think you're going to hide behind doors as you're still behind that door using a ploy for the purpose to circumvent the restriction.

Including high end skip trace tools.

Just a reminder of where you are buying in the economic cycle :) (If you don't care about CA or the SF Bay, skip to the bottom for US)I'm not a chartist, but I was surprised how regularly unemployment in CA reverts relatively quickly after getting down to almost exactly 5.0% in the last few decades.. 5.7% as of Nov 2015.

Skip two weeks ahead......When I met the Lowes appliance guys at the house they were unable to complete hooking the ice maker up because the water line was too short to reach the fridge.

I would have started learning about investing in RE in college rather than gambling on stocks while taking notes.If I have the knowledge and drive back then I might have skipped a party to buy a house or two. 

If so, you'll probably want to use Accurint, Merlin ir similar software to locate your party or a professional skip tracer.

I came across a few properties that are vacant and the owner is deceased with no will, No children but some family members I could skip trace.

Do we still receive the carry over basis even though she skipped her son and gifted the property to us, her grandsons?

Unfortunately, I've have been burned by previous tenants for skipping out on the utility bills.