Mini-Mig Bill of Materials

[nBit7]

That part is not suitable for the Minimig. It is a 5V only part. You'll need a MAX232 (or clone) that is specified to operate at 3.3V with 0.1uF caps.

To the best of my knowledge the MAX232 (from MAXIM) is a 5V only part.
http://para.maxim-ic.com/cache/en/results/5021.html

The MAX3232 is the 3.3 - 5V part.  Checking the datasheet for the MAX3232 against your schematics the pinout matches.

[nBit7]

A MAX232A (5V only) may work in the circuit but I wouldn't advise it.

A correct part number for the Maxim brand part is:
MAX3232CSE+  or  MAX3232ESE+
see the data sheet:
http://datasheets.maxim-ic.com/en/ds/MAX3222-MAX3241.pdf

The CSE or ESE refer to
C = Operating Temperature Range C (0°C to +70°C)
S = Package Type S (SOIC 0.150")
E = Number of Pins category E (16 pins for this package)
or
E = Operating Temperature Range E  (-40°C to +85°C)
S = Package Type S (SOIC 0.150")
E = Number of Pins category E (16 pins for this package)

The 3 in front of the 232 is what designates it as the low voltage compatible part.

If you look at other brands be very careful to check the pinouts and package size is the same.

[nBit7]

With the 0805 resistors, Parts list says Metal Film 1%, Digikey have them, but only 0.1% and 5% tolerance. 5% or 0.1% tolerance ?

Thick film, Metal film, Thin film.  All would be fine here.  pick whatever is cheapest/easiest to get.

After all 2k2 is 2200Ohms, but 2.2k is also 2200Ohms yes ?

Yes.

[nBit7]

560M is 560Megohms (560 million Ohms, but resistors don't go that high)

Actually they go much higher: 6000000 M (thats 6000G or 6T).
http://www.vishay.com/resistors-discrete/res1G/

Must admit I have have never seen one in the flesh (unless it was called an insulator).  I have seen and used 1Gig Ohm.

[nBit7]

they recommend a 10uF Capacitor on the Voltage input SOurce, but Dennis has a 100uF, my thought is by having a Capacitor that is 10 times the capacitance, he *REALLY* wants to eliminate noise on the board.

The 100uF will only be good with low frequency ripple (something that the regulator is good at).  To get rid of noise ( due to input rejection ratio) you would need a low capacitance tantalum or ceramic (ie low ESR and ESL). Having a large reservoir cap is a good thing.  But ideally a 1uF to 10uF tantalum (or maybe a 100nF to 1uF ceramic) should back it up to provide for the high di/dt loads of this type of circuit.  With engineering there is always a trade off.  Higher capacitance tends to means lower performance in other areas.

[nBit7]

And the Pic Firmware, I tried Hi-Tech Picc lite, but it appears to only support 16 series Pic's not Series 18.

That's correct there is no free c compiler that supports the PIC18 series.