As a first approximation, assume that integrated circuit (IC) package dimensions are standardized enough to be interchangeable, until you have information that shows otherwise - especially when dealing with through-hole parts. There ARE minor variations and nuances from one manufacturer to another, and even a few variations specific to one manufacturer, but when it comes to the locations and sizes of electrical connections you may assume that things which appear to be interchangeable, are in fact interchangeable. You can confirm this with a cursory check of a few basic dimensions on the footprint.
I presume you intend to use the through-hole version of the PICAxe parts, in the "dual in-line packages" (DIP). These have been widely used since the early 1960's; I don't recall whether Fairchild, or Texas Instruments, are credited with the original invention. The connection pins are spaced on 0.1" (2.54mm) centers, sometimes called "0.1" pitch". When the pins are straightened to be perpendicular to the package's seating plane, they are 0.3" (7.62mm) apart for devices with about 20 pins or less. For devices with more pins, wider row-to-row spacings are used.
To illustrate what I said in my previous post I created a custom schematic symbol for a PICAxe-20M2. I opened the KiCAD symbol editor, loaded the symbol for a PIC microcontroller (the 16F1829, as I recall), and created a new library. I gave the symbol a new name and changed some of the other administrivial stuff (datasheet, description, etc). I then re-named and regrouped the pins to suit a fictional project. Here's how it came out:
As you can see, my imaginary project uses five A/D inputs and creates three PWM outputs plus three other logic outputs. There's an I2C port - possibly connected to a serial EEPROM - plus a classic asynchronous RS232-like serial port. The PICAxe pin "C.6" might be a logic input or may get flagged with KiCAD's "unconnected" symbol. (I never liked to use the PIC's MCLR pin if I could avoid it - being part of Microchip's ICSP scheme imposed some constraints on what I could connect to it, and I just felt squeamish about using a pin for general-purpose input, when it's original primary function was to receive a hard RESET signal.)
The PICAxe power and programming pins round out the symbol. This fictitious project must use the uC's internal clock oscillator, since the symbol doesn't label any pins as "XTAL" or "CLK".
Are you starting to see how much information you can convey about your design, simply by how you drafted the microcontroller's schematic symbol? I have attached the KiCAD file containing this symbol, for you to study, dissect, or alter as you wish. You may want to compare it to the symbol I started with.
PICAxe.dcm (256 Bytes)
PICAxe.lib (1.2 KB)
If you have more questions (I'm sure you will, if you see your project to completion) or get stuck someplace, start a thread with your question. Give some indication of what you've already done to find an answer and you should see a reply within a couple of hours. The majority of Forum members seem to be in North America, but others are in Europe, Singapore, India and China so time zones aren't the impediment you may think they are.
Well, it's after midnite here in St Louis (roughly the center of North America) and my wife has indicated she is in bed, waiting for me to perform certain Husbandly Duties. Keep us informed of your progress.