2. i don't know the maximum size supported by TeXtr. it reads only .txt files;
3. the only modification i've made into Firefox os apps are two lines into the manifest.webapp file that are needed to show a cursor that substituting the fingers touch. is not the best way, but the apps are almost usable (for a feature phone).
sometime,like in the pdf reader,i had to modify the index.html to have a better interface usable for our devices.
that's all.