Understanding some mash profile settings

Greetings folks. I've decided to finally post a question that has been bugging me for some time. I have a feeling it's basic, but the searching I've done have not cleared things up.

I mostly do simple all grain batch sparge. I use the "single infusion, medium body, batch sparge" as my mash profile. I check off equal batch size and Drain tun before sparging.

Beersmith advises me to mash in with about 4 gallons of water, and then batch sparge with about 6 gallons of water. That doesn't seem to be equal batches to me, especially with the absorption in the mash! Am I doing something wrong, is there some setting I missed, or (most likely) do I just not know what I'm doing?

Thanks in advance for any advice or help.

I take it from your description that you are using the mash profile inherent within BeerSmith.  To get equal runnings from this, you will need to reset the water to grain ratio in your initial infusion.  The easiest way to do this is to take all the water you need (~4 gal + ~6 gal = 10 gal) subtract the water which will remain with the grains (for this example, let's say it is 1 gallon) and then divide the result by 2 (half for the infusion and half for the sparge.  This will give you ~4.5 gallons (~10 gal - 1 gal =  ~9 gal, ~9 gal / 2 = ~4.5 gal). Now take the infusion water and add back in the water which will be absorbed by the grain (1 gal) [~4.5 gal + 1 gal = ~5.5 gal].

Now go into your mash profile within the recipe and edit the infusion step.  Where the box is for 'water to add', type in your result (~4.5 gal) and save the mash step.  BeerSmith will now recalculate the infusion ratio of water to grain to give you that amount of water in the infusion step.  The runnings from this should be about the 4.5 gal with 1 gallon retained in the grain.  The recalculated sparge step will read the remainder of the water (~4.5 gal) that should be about equal to your first runnings.

Save the profile if this is what you want to do for more than this one recipe (click on the little disk icon next to the mash profile).  If the grain bill is about average for what you brew, the infusion water will be recalculated based upon the amount of grain for that recipe.  There may be some variation from recipe to recipe, but the calculated running will be pretty close to even.  If you want to use the profile in any recipes you already have written, you will need to update the mash profile within the recipe to give it the newer settings.

I also have a basic question.  When I copy a recipe for example from the Northern Brewer recipe list I see that the mash profiles are coming as a preset profile.  Is this something I would change or is this what was originally setup with the imported recipe.  I can see that I could change the fermentation profile from ale, single stage to ale, two stage and change the fermentation for the recipe.  I am thinking that when I get some one else's recipe that I would use what showed up and maybe change it some day when I had a lot more brewing experience to know what to do with this.

It is your choice.  My preference would be to change the equipment, mash, and fermentation profiles to my personalized profiles.