Adding New Columns And Moving Old Columns

Using VBA... I have Column N (eFIUnitRebate) which I want to swap with Column M (FFUnitPcnt)

Now with Column M as eFIUnitRebate and N as FFUnitPcnt I want to create an extra column (adjUnitCost) where Column N is and push FFUnitPcnt to become column O, etc.

Here is how the whole process should work:
Swap M and N
Insert new Column in N
Insert new Column in P
Insert new Column in Q
Insert new column in R

There is more information on the sheet after these columns so for all column inserts it needs to push whatever was there over.

So the layout is as follows:
J
K
L
M
N
O
P
Q
R

Units
UnitCost
UnitRebate

[Code] .....

These columns are thousands long, so I would like the formulas for them to be applied to the whole column as well.