hi  regarding installing the material hinges  -i do not at all like the standard slotting method that i often see used-   i feel you are gessing the hinges are glued in as they s/b   -loose hinges will do your plane in-  especially over a long period of many flights-   my method is to mark the location of the hinges    i  draw a line on the the stab  for example-at its trailing edge -half way between that edge -i then cut out a square the size of the hinge -in the balsa with an exacto knife (no hindging tools required ) -down to the line drawn-remove that  square of balsa-   put thin CA in the cutout-  let it dry -lay in the cloth hinge-apply thin CA again-(i am now sure the hindge is TOTALLY glue down ) and replace the piece of balsa i had cut out prior on top of the new glued in cloth hindge- sand and smooth     you now have a hindge you are sure is not going to come loose in the future-none of mine have in 20 years  do be sure you have a hindge located very close to your control horn-as that will allow the control horn to apply the proper force to the control surface-and not just not be flexing that control surface    do yank and pull on any hindged surface you may question-as it is better for you to pull it off -than for it to come off in the air    on none material hinges -it is a good idea to pin the hinges-drill a small hole through the hindge-install a tooth pick with glue-cut it off ( a large nail clipper works good here )-and sand smooth- it is real important to keep those hinges were they belong to keep the plane flying for many years