To your third question:
You mean a reaction of ethanol with the acetylic acid that accure when u oxidise it ?
I dont think there will be one , maybe there could be one if u work with conentrate H2SO4 as catalyst.Because you can also oxidise Ethanol in appearence of OH- , and if u want to create ethyl ethanoate ester you will need an acidic medium with concentrate H2SO4 which will also bind the resulting h2o of the reaction of ethanol with acetylic acid.
By the way you can make Propanoic acid like this => C2H4 + CO + H2
The reason why the glycerin catchs fire is that at some point the glycerin forms some product (Acrolein dont know the english word for it maybe its the same ) , an unsaturated carbon-hydrogen compound which starts to burn, actually thats what i think im not sure though.
hope i could help you abit