What are the factors that affect the chewiness, softness, moisture of bread based desserts like cinnamon rolls?

I'll try to be specific without getting into too much detail here:

1. The chewiness (AKA elasticity) - of dough is due to the formation of gluten. This is affected by:

   • The amount of flour used (gluten is the result of water and various proteins in flour, specifically glutenin and gliadin);
   • Type of flour used (high-gluten flour such as bread flour gives means a chewier result);
   • Fat content (fat insulates the proteins from the water, slowing gluten formation);
   • Sugar content (in order for gluten to form, it must be dissolved; a high sugar content saturates the water and prevents dissolution of the proteins);
   • Baking time (up to a certain point, until all of the available proteins have been used up).
     
     

2. The crust (I assume this is what you're referring to by "softness") - is primarily the result of the Maillard reaction, which requires an amino acid and a sugar as well as heat. The longer and more quickly the reaction carries on, the crispier and browner the crust will be. The factors are:

   • Baking temperature (higher = crispier);
   • Baking time (longer = crispier);
   • Moisture (less = crispier). This has an effect because the evaporation temperature of water (100° C / 212° F) is lower than that required for the Maillard reaction (154° C / 310° F), so the reaction can only take place once all water has evaporated or been converted to gluten.
   • Acidity (pH) also inhibits the Maillard reaction but this is not normally a concern in bread.
     
     

3. Finally, the moistness of the bread is essentially a combination of the first two:

   • Higher fat content means less gluten is formed and more of the moisture is preserved, as long as it doesn't evaporate. The fat itself also adds a certain amount of moisture as far as mouth-feel is concerned.

   • Higher sugar content also preserves more of the moisture and using a wetter sugar (i.e. brown or muscovado) provides some moisture of its own - although the latter can easily evaporate with over-baking.

   • Longer baking times cause more of the water to evaporate, which reduces the final level of moisture in the finished bread.

   • Higher baking temperatures also cause more water to evaporate. However, it's usually a trade-off between higher temperatures or longer baking. A good recipe tends to be optimized to provide a slightly crispy crust without over-developing gluten or drying out the bread.

If your bread (or similar baked product) ended up too dry, it's probably because you over-baked it or baked at too high a temperature. If it came out too chewy (glutinous), you might have used too strong a flour or not enough fat/sugar.

Some of the most important factors that affect texture in this way are: sugar content (brown), fat content, milk content, and egg content. When you make cinnamon buns, you want to use a sweet dough (never lean), and sweet doughs always have a higher concentration of these ingredients.

Fat, water, cooking temperature and cooking time.