The nomenclature of mineral acids
The English names are not very systematic, they just give hints.  In principle you have to either memorize the name-structure correspondence, or know "all" acids of sulfur, so based on the name you can guess what the structure it corresponds to.

In addition, the hypo having one oxygen less is just a shortcut. What the names refer to is the oxidation state of central atom from lowest to highest.
Broadest range of acids are for chlorine: hypchlorous - chlorous - chloric - perchloric.

Answer 1: Please refer to the Wikipedia page on sulphur oxo-acids
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The $\ce{H2S2O5}$ acid drawn is hypothetical one, but it's fine to have a name for it. Note, that sulfur is in low oxidation state.
In the pyrophosphoric acid, the phosphorus is in high oxidation state and has extra oxygen in between them.

For the summary formula $\ce{H2S2O3}$ you try to mix these properties, putting "extra" oxygen between sulfurs in low oxidation state. This won't work. The acid you should get when you attempt to obtain this one will be the thiosulfuric acid, where one sulfur mimics oxygen as $\ce{S^2-}$. 

Answer 2: Chemistry of phosphorus is distinctly different from sulfur. 
Phosphoric acid and Phosphorus acid for the acids with one phosphorus atom.
Your formula $\ce{(H3PO3)_{$n$}}$ with $n=2$ is not really justified, the name corresponds just to the formula on hypophosphoric acid.