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Don't scrap it yet.  You need to put the pin numbers next to the voltage readings.  The only thing close to +15 I see is "14.81", but it's unclear which pin.  That would be OK for pin 8.

IC2 doesn't have any sign of power.  Should have +15 on pin 8.

IC7 and 8 supply the power to the rest of the board.  Check those.  You need to get +15 on IC8 Vo, and approx. +7.5V for "VB."

Shawnee, you don't have to use a balanced output to use an XLR.
I'd figure I'd mention this, since your original post mentions nothing about balancing.
Here's some more good reading on the subject: http://www.douglas-self.com/ampins/balanced/balanced.htm

There are many ways, and many types, of XLR output schemes, most of which deal with pro audio or other signal problems that a bass preamp doesn't necessarily need to address.  The "common sense" seems to be that balanced is always better, but in practice a unbalanced output is usually OK.

For a basic unbalanced XLR output, yes you should buffer it and set the impedance to 1k or less, and attach the output to pin 2 of the XLR.  Tie pins 1&3 to ground.  Balanced inputs will accept this.  No extraneous circuitry required.

Pardon my ignorance - I'm learning how all of this actually "works" still.

I have a Mudbunny board I'm populating that I wanna play, and I don't have the 100k pots(on hand - order placed later today). I have a couple 250k and a 500k pot handy. I know I could use a couple resistors across lugs 1 and 3 to get the "correct" pot value . I'm of the understanding (perhaps incorrectly) that the resistor trick is only to be used in a variable resistor situation, not in a voltage divider one.
My questions:
Does it matter which way they're being used as to do the trick?

Putting a resistor across lugs 1 and 3 will lower the overall resistance.  Doesn't matter if voltage divider or variable resistor.  A resistor from lugs 2 to 3 is common for making linear pots work like audio pots.
If you're trying to finish a build, just wait for the 100k pots.  If you're experimenting, and just want to clip pots in, then 250k pots will be fine for testing purposes, and attach 220k resistors across 1&3 to see the difference.  The 100k is by no means a "critical" value.

What function are these pots?
My guess is Voltage divider for Vol and Sustain as I'm seeing 9v come in lug 3 of both.
Tone seems to be variable resistor? Blending between two caps to ground?

Volume and sustain are passive, ac voltage dividers.  There is no 9V on any of the pots.  The caps block dc.  Anywhere you see a cap, consider that a dc "roadblock."
Tone control is a passive ac voltage mixer.  The inputs are 1&3, and the output is 2.  The output of Q3 is split into a high-pass RC filter, and a low-pass RC filter, and the outputs of those filters connect to tone pot's 1&3 "inputs."

Ziggy,
The jack you're looking for is probably this one: http://www.allparts.com/EP-4163-001-4-Conductor-End-Pin-jack_p_1381.html  Allparts part number #EP-4163-001
Seems like most of the replies here thought you wanted to know about pedal and amp jacks.
While the pedal world usually uses the "short the ring" trick for the battery, the acoustic guitar world generally does not use that trick.  Open up any Fishman or LR Baggs on board preamp jack, and you'll see something like what I linked to above from allparts.
This avoids a "no output" problem from a TRS cable, and allow for dual signals on one cable (magnetic pickup on tip, piezo pickup on ring).

There are 3 solder lugs on the EP-4163.  Shortest one is for tip connection (main output), middle one is for ring (aux output), and the one closest to the sleeve connection is for the battery negative, and it will switch to ground while keeping the tip and ring isolated.  (Double check the operation of the 3rd lug, as it's been a few months since I had to mess with one of these... but I can't think of any other way it would work. And they do work!)