#3
This is easier and MUCH more terrible, but much easier and cheaper.

A First Act GoAmp (it'll turn on when you plug a guitar in)...


(You said cheapest and easiest, so...)
#6
http://www.runoffgroove.com/littlegem.html
http://www.flickr.com/photos/54804764@N00/401719542/

as for the switch and headphone jack you can add those very easily... for an on off switch all you need to do is wire a switch with the positive from the battery that cuts it in one position and lets it connect to the circuit in the other.
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Faded Gibson SG Special - Black ice mod
Seymour Duncan SH-5 in bridge
B-52 AT 112
Ted Weber Mass100 attenuator
EHX Small Clone
EHX Metal Muff
DIY Modded tubescreamer
Dunlop 535Q Wah
Wax Potting tutorial