I think methanol is more volatile than ethanol. Methanol will evaporate quicker because of its chemical structure. Methanol has a smaller structure because it has one less H-C-H group compared to ethanol. This means that methanol has lower boiling point than ethanol which should mean that methanol will definitely evaporate faster.
i always have a filter on my lens so i just need to blow off whatever dust that somehow gets on the lens element.
as for filter, tried eclipse but had hell of a time clearing the streaks. finally went with good old soap and warm water ;p i also learnt not to wipe the filter dry. better to put it aside and let the water evaporate. once it is try use lens tissue to clean.