Spanish phonetic spelling

Hi, Everyone:

As I mentioned in my many other messages, I am now adding my quarter's worth
to the discussions. One of the old messages (forgive me if this is already
known and some of you are going, "Well, duh") talks a bit about Spanish
spellings, y for I, etc. I found the following in an Hispanic Genealogy
book (Sorry, it's late and I'm too lazy to find out which book right now):

Interchangeable Letters:
i-y: used interchangeably until less than 100 years ago.
b-v: used interchangeably even today- also "u" for "v".
j,x,g: used interchangeably by 1550, by 1850 "x" not used as Spanish "j"
sound when used before "i" and "e".
c,s,z,ss: used interchangeably in early Spanish, along with "x,". C,s, and z
still used interchangeably, depending on location.
i-e,a-o,a-u,o-u: used interchangeably in early Spanish and in some regions
still today.
ch-ll: used interchangeably depending on region.
b-p,c-g,d-t: as late as 1700, these interchanges can be found, a carry over
from Latin.
l-r: used interchangeably, some regions more than others.
m-n: used interchangeably between vowel and consonant in words, significant
specifically in names.

Latin Influences:
c-q: Latin "qu" becomes Spanish "cu", such as from quando to cuando.
ff-ph: "ph" introduced into Spanish from Latin to express sounds in
Greek-origin words, such as filosofia to philosophia.
Impure "s": from "es" sound at beginning of words in Latin, sometimes "is,"
later dropped, such as espiritu to spiritu.
Insertion of letters: when Latin spelling is followed closely, such as santo
to sancto, bautizar to baptizar.
Letter "h": may be omitted or added or substituted by "g" or "f". "F" is
used in words now having "h", such as fijo to hijo. Persists into 16th and
17th centuries. "H" may be replaced with "g", such as guevo and huevo. You
can pronounce the words outloud, the "h" is silent, so the meaning will
become clear.

Confusing Letters:
f,i,j,s,t: no linguistic distinction between "i" and "j" until after the
15th century, not totally defined for two more centuries. Sound out the
word to see which it makes sense with of these five letters.
a,o,v,c: often confused with one another in early handwriting.
r,x: use of "x" for "r" very common, even up to the 1850's.
s: can be written in various ways, so be careful.
t: often resembles many letters other than a "t".
Double letters: sometimes no linguistic significance, or represented sound
needed, such as "nn" for Spanish "n" (pronounced "enya") and "rr" for
trilled "r". "Gn" also used for Spanish "n" (pronounced "enya) prior to the
17th century. Some double letters are abbreviations.
Linking letters: occurs in older Spanish manuscripts, one word is linked to
the next.
Suppression of "e": In writing, "e" frequently appears and disappears at the
end of words.

Also, because spelling was done phonetically, you can determine where an
ancestor was from in Spain by how they spelled words, some of which are
regionally distinct by Spanish provinces, whether associated with the church
or nobility, etc., because of how they anunciated their words.

I know this is a lot. Perhaps I should have posted it differently? Or, is
this okay?

Corrine Ardoin