I can answer your breeding question!
To put it shortly, a good match is when the weaknesses of Horse #1 are offset by the strengths of Horse #2, and vice versa.
Essentially, you don't want to pair two horses of the same weakness(es) as you will risk the product being a lower rated foal.
Looking at Fortina, we can see from her wk4 that she isn't outright weak in anything in particular. Moving onto her wk7, we can see that her strengths are Hrt, Scp, and Str as she went up in those traits. Mv, Int, and Spd did not increase, so these may be average or weaknesses.
In her wk11 and wk15, her weaknesses are finally revealed! In wk11, she was not up in Mv or Spd, and in wk15, she was not up in Mv.
To me, this means that Mv is her greatest weakness, followed by Spd, and then possibly a tad weak in Int. These are the traits she needs offset, aka the stud I send her to needs to be strong in these.
Looking at Stolas, we can see from his wk7/14/17 that he is strong in Mv, Hrt & Speed, and weak or average in Int, Scp, and Str.
Wk 10 shows that his greatest strength is Spd. Wk11 shows again that he is weak in Scp. Wk18 also shows a weakness in Scp and Str.
Stolas and Fortina are a good match as Stolas is strong in both Mv and Spd, where Fortina is weak. Where Stolas is weak in Scp and Str, Fortina is strong. Their only problem point is Int, where neither are especially weak nor especially strong.
This match has produced three WWWs, all aided with an Int glass to cover a potential weakness there.
If you have questions or need any help when looking at matches, feel free to message me! :)