Are you building a masonry addition (2 layers of brick thick) or a brick veneer (brick faced) addition?
Most modern construction is brick veneer and windows are attached to the studs just as in a frame house. The brick is only a siding.
The windows are installed before the brick is placed.

It appears you are really lookiong for how to attach replacement windows in the existing brick openings.
There are very few contrators who will even try to correctly install windows into brick openings.
If the house is brick veneer (one layer) the nailing tabs are removed from the remodel windows (if they even have them) and the windows placed and caulked to the existing brick.
If the house is masonry, tapcons can be used to fasten new windows into the masonry.
Most of the widow replacement jobbers want to lne any opening with wood (called 'bucks' inthe trade) to simplify fastening the windows.

You are correct, we are installing a brick-faced wall of roman brick over the wood framing.

The homes original sill heigth's do not meet code in the BR's and we will be changing sizes and locations of some others. I anticipate and have started a brick removal from the sill's up, for the work.

As you stated brickeyee, "bucks" were used in the previous re-window and are very unsightly.

I'm curious as to the correct way that the new window frames will or should be finished at the interface with the brick. As I mentioned, this home does not appear to have had any type of trim surounding the original aluminum/steel frames.

Do I need to order a specific type of frame that is meant for this style finishing?

The home is a 50's single story with a 5/12 pitch hip roof and has wide 24" eve's and is entirely bricked. I love the look of the windows having a minimal impact on the visual aspect as the retrofits I see (mostly in white) "stand out" with thier grids and muntins.

I'm trying to educate myself on both an apreciation for the correct style and proper assemble/finish techniques.

TIA

The problem is how the house was originally built (and it is still pretty much the same now).
The windows are inserted into the framed openings before the brick is placed. This effectively traps the window. The nailing flange is between the brick and the wood and there is not enough room to get the nails out. A lot of sawzall time is often needed to prep the opening and the window replacement guys do not want to bother.

Even the window manufacturers for the most part stay away from brick openings.
You can look around on the web for installation instructions for brick openings, but the last time I bothered all the sheets called out bucks. I agree they often look bad if you do not have a house style that lends itself to brick mold to cover the bucks.
Thicker aluminum can be used to cover bucks also. A local sheet metal shop should be able to cut strips of ~0.40 that you can mount using stainless flat head screws or aluminum screws into the bucks.

I have installed replacement windows in masonry openings by sizing them to the brick opening less ½ inch and then using polyurethane caulk to fill the gap.
Either tapcons into the brick or nails into the wood framing hold things while the caulk sets up.
Polyurethane caulk is more than strong enough to hold the window in the brick opening all by itself once it cures.

You are generally not required to make new windows meet the modern code when replacing them, but you can lower the openings if you wish of course.

Save some of the bricks you remove. You will need them since cutting bricks in half while they are still part of the wall will result in some that crack in the wrong place and have to be removed completely and replaced. It is better to remove the bricks one whole brick further than needed, cut them and mortar them back to get a clean edge. The opening ends up Âtoothed on the sides until the cut bricks are put back. It can be a real mess to clean the mortar off when needed.

Thanks brickeyee for any and all tips...

As you mentioned there is little to no info concerning this matter readily available. Seems that it mostly was "tribal knowledge" by masons from a past generation, unfortunatley.

I have removed, cleaned and have in dry storage nearly 1500 bricks, I have that many again to remove. This will allow me to reframe and install my new aluminum windows in a proper and hopefully long-lasting manner.

My munincipality regards window replacement as a permittable project being we have to install windows that meet STC38 ratings. The inspection requires that a b/r sill height be 44" or lower for egress, mine are 48". The homes windows fit tight to the bottom of the header or soffitt.

My intentions were to brick up-to the window frames edge, atleast close enough that a bead of caulk at the frame would fill the void. Is this ok or even recomended?

Not sure if this helps you in any way, but last year I did an extensive renovation on a recently pruchased 1940's brick veneer house. All of the operable windows in the house were replaced with new wood casements. Many of the windows were enlarged, but even those that weren't required removing some of the brick around the window and all of the brick sill. The removed bricks were cleaned then reinstalled by a mason.

I was afraid that it would be obvious where brick was removed then replaced, but the finished job is seamless. I doubt than anyone but a mason could tell where any brick was disturbed.

James