By breech load, I assume you are talking about breech seating. That said, if you are going to buy powder, get Swiss 1F (yes, 1F for your 32-40). If you already have black powder on hand, use what you have. After priming cases, use a drop tube to fill case and place a thin card wad in the case mouth to hold powder in place.
Set your breech seating tool to the length of your rifle's chamber. To seat a bullet place a 32 cal 1/16" felt wad in the seating tool, then place a 32 cal card wad in the seating tool, followed by the bullet. When the bullet is seated, it will have a the card wad against its base then the felt wad which will be right at the loaded case mouth when loaded. This loading process is a good place to start. 
Now you can start with various fouling mitigation routines such as wiping between shots, using a blow tube, etc.
Use water with a few drops of dish soap added for bore cleaning. Oil after the bore is dried.
I have also heard good things about Olde Eynsford powder but have not yet tried it.
Good luck

Swiss and Olde Eynsford produce the softest fouling, and also slightly higher velocities with identical charges than regular GOEX.  Most shooters seem to like either 1.5F in larger capacity cartridges with a tendency to go to 2f in smaller capacity cartridges, though there's quite a bit of overlap.  I've been experimenting with 1F Scheutzen in a larger capacity military bottleneck (Italian Vetterli) lately with promising results, but really haven't shot it enough to form strong opinions.  Lots of folks are getting good to great results with Swiss and OE in a wide variety of cartridge as well as muzzleloading guns.

RSW, I noticed that you advocate seating a wad in the seater under the bullet.  I've also found that this is a good thing for breech seating with black powder.  I think SPG wrote about it once too.

I have had decent accuracy with Fg at 100m but I always get more vertical by 200m so I've got more experimenting to do.   However, my Winchester 1885 in .38-50 RH is currently my most accurate rifle at 200m.  I use 59gr of Fg.   I have to wonder if that's the perfect black powder chambering for short range.

Chris.

   I have an old target in my possession, found in a 1922 RIFLEMAN magazine (addressed to one CLARENCE LYLE, MEREDITH NH)  showing a 1.75" 10-shot group.  On the back of the target is written:   "10 ahots, 200 yards, M&E R. (muzzle and elbow rest?) 32-40 Zischang-Ballard.  No. 2 1/2 primers.   42 grains weight FFG Black.  175 grain bullet.  Seated in throat with seater."   Looks like CLARENCE had found a good recipe. 
CHRIS
RGChristensen
   

It does look like that worked for him .  Black powder can indeed do well once you get all of the variables tuned to your liking.   

Chris.