When it comes to commas, it is correct to put comma before and when you have a list of items that are three or more items such as this example:

I need a hammer, nails, and a plank board to be nailed to the idiot contractor's forehead.

You don't use the comma if it is just two items like the example:

I like to use paper and pen when preparing construction documents.

LOL... Concrete continuous spread footing or simple continuous footing or grade beam. I would lean towards the continuous spread or simple continuous footing given the width is more the the depth. I don't usually call it a grade beam until the depth is more than the width and denotes a 'beam' profile. 

Then we are splitting hairs on that with exact discretion.

Lineal is a proper english word. 

Here is an example of conjecture on this topic:

http://www.usingenglish.com/forum/threads/81174-Lineal-vs-Linear

A quote from here:

https://answers.yahoo.com/question/index?qid=20080211075343AAGg8Ln

"In construction, lineal describes a quantity of material that has an implied width dimension, and linear describes a distance regardless of width. Consider the following example: "We need to replace a single metal panel, and the building's sidewall is 12 linear feet to the eave, so we will need to order 12 lineal feet of metal."

In construction, the term is valid and both words have subtle but distinct meanings. So careless interchanging is misuse of the word.

Lineal has two definitions. One definition refers to lineage and the other is used in application of line-based mathematics. Engineering has another application of the term lineal. 

We are talking nomenclature. This is dependent on the context. The code could be correctly applying it but I didn't check the code section to verify if it is being correctly applied in the context. 

Lineal is an alternative word long established in the English language. 

One is more like old/middle English and the other is contemporary modern English.

This depends on perspective. If you are measuring something with a known consistent width, in construction nomenclature you would use lineal feet like how many lineal feet of 3" steel pipe? Or lineal feet of a specific crown molding of known dimensions with width and depth but not length. If you are measuring a line of travel then linear feet. 

More often than not, it is more like a interchangeable word with evolving application. Lineal is more an archaic form of linear. In 1832, lineal was used to measurement of length. Over time, lineal vs linear debate is more about evolution of the English language usage. When you measure length, the term was called Lineal Measurement. This is supported chronologically in the Webster dictionary from 1832. I have a scanned PDF of that dictionary. Linear was used as a descriptive adjective of an objects shape like a 2x4 lumber is linear in shape. When we talked about measurement of its length, we talked lineal footage. However, in time, this application of terms evolved. 

In construction trade, this is matter of opinion than necessarily hard line facts because it isn't universal but lineal as in 'lineal foot' would be used when you are referring to an object with known widths and the measured length. While you wouldn't call something a linear foot,  linear foot maybe used to refer to measurement of distance between buildings for example. 

In contemporary parlance, a person may choose to ignore old traditions and call any measured length of lineal foot as linear foot and relegate lineal to reference of lineage.

It isn't so clear a right or wrong but choice, locality, etc.

To a degree, they are sort of interchangeable words. Lineal is more archaic, now.

True... but grade beams are usually deeper than they are in width in cross section. It needs that along with the rebar configuration to support 'spanning'. 

It differs from "continuous spread footing" or "simple continuous footing" even though all three are types of continuous foundation or continuous footing foundation systems vs. isolated. Simple continuous footing simply is the common type found under say.... a C.M.U. wall foundation with like 3 or 4 horizontal rebar about 2" from the bottom of the footing. A continuous spread footing is usually a little wider and designed to spread load and has a different rebar configuration with rebar and 'temperature bars' (rebar in tranverse the normal rebar span along the wall length).

The grade beams require a very different and often more extensive rebar configuration. They all often is supported continously on soil or bedrock unless 'deep foundation' systems are employed. I agree with the term but there is also common visual characteristics of one from the other in case you don't have the plans or able to see the rebar configuration which also isn't always the same. Some architects in the past have been crazy with their extensiveness of rebar.

Oh trust me, in some of these cases, it definitely was Architect because in those days, Engineers weren't ordinarily involved with buildings at all. In those days, the architect was the engineer because the role was just one of the responsibilities of the Architect.