First, tails: On single prop planes of this era, I have one personal experience, the Folkerts SK3. Initial versions were made with everything true to scale. That was a mistake. I could BARELY control the lateral direction because the tail was too small - a common problem of planes of the early aviation era - coupled with the fact that the GIANT nose and forebody were effectively blanking it at sideslip angles. After scaling up the vertical by about 10% in AREA, it behaved better. It was still friggin' scary to hand-launch, but that's not because of the tail. 
Looking at your pictures, your horizontal doesn't look too bad, but the vertical definitely looks undersized. I would start by increasing the vertical area by about 20%. I don't know all you dimensions off-hand, but it looks like you could probably just make the tail about an inch or two taller and start there.
Wings...
A "flying strut" like you have here is definitely not a trivial feature. @willsonman rightly points out the complicated airflow interactions between the "struts" and the main upper wing, but it's worse than an annular wing because at least with that you have circular-symmetry. Here you have basically a massive-dihedral "V-wing" biplane, where the lower wing has dihedral but the upper wing doesn't, and the lift of the lower wing is "sucking down" on the lift from the upper wing. I think this may be why most successful "normal" biplanes have the wings staggered, to reduce their interactive effects.
In looking at pictures of the real thing, it appears that the 'strut wings' are thinner relative to the main wing than you've made in your model. This could help because the thinner wing will make less lift, reducing the accelerated-flow effects Josh talked about. The lift-interactions should be less pronounced - more like his suggested flat plat wing than a highly-cambered airfoil.
If you reduce the thickness of the lower strut-wings it will also reduce the camber. This will reduce the lift they make, which should also reduce their effect on the upper wing.
You should also note the vertical struts on the original are not simple rods, they are "blades". This isn't for strength, it's for drag and clean airflow. A cylinder has 10-times the drag as a flat-plate of the same thickness and a few "diameters" long, simply due to turbulence. Try putting a blade of foamboard behind the dowels you have there. For best results, taper the blade to an edge.
Looking at your pictures, your horizontal doesn't look too bad, but the vertical definitely looks undersized. I would start by increasing the vertical area by about 20%. I don't know all you dimensions off-hand, but it looks like you could probably just make the tail about an inch or two taller and start there.
Wings...
A "flying strut" like you have here is definitely not a trivial feature. @willsonman rightly points out the complicated airflow interactions between the "struts" and the main upper wing, but it's worse than an annular wing because at least with that you have circular-symmetry. Here you have basically a massive-dihedral "V-wing" biplane, where the lower wing has dihedral but the upper wing doesn't, and the lift of the lower wing is "sucking down" on the lift from the upper wing. I think this may be why most successful "normal" biplanes have the wings staggered, to reduce their interactive effects.
In looking at pictures of the real thing, it appears that the 'strut wings' are thinner relative to the main wing than you've made in your model. This could help because the thinner wing will make less lift, reducing the accelerated-flow effects Josh talked about. The lift-interactions should be less pronounced - more like his suggested flat plat wing than a highly-cambered airfoil.
If you reduce the thickness of the lower strut-wings it will also reduce the camber. This will reduce the lift they make, which should also reduce their effect on the upper wing.
You should also note the vertical struts on the original are not simple rods, they are "blades". This isn't for strength, it's for drag and clean airflow. A cylinder has 10-times the drag as a flat-plate of the same thickness and a few "diameters" long, simply due to turbulence. Try putting a blade of foamboard behind the dowels you have there. For best results, taper the blade to an edge.
