less fresh egg whites work heaps better. even egg whites that are 1 week old are better, because the protein starts to break down. they become more watery, and are easier to beat. you get a glossier meringue.

make sure your utensils are very clean so they is no oil residue, this can lead to a flat meringue.
a pinch of salt at the beginning when beating the whites will help them aerate. add your vinegar and vanilla at the beginning. beat for a minute or so before adding the sugar. pour in the sugar slowly. whip until firm peaks form (you should be able to tip the bowl upside down and it wont run out). room temp egg whites work best (make sure there is no egg yolks at all in the whites, the fat in them causes the whites to not foam up).

i recommend piling it up also. you want to have it similar size to how you want it to turn out. it will rise a bit but not heaps. not sure on temps, but i know if you leave it at a low temp for a long time it will become dryer.

i dont think you need to pipe the meringue mix, unless you are doing cute individual ones. the piping will take out a bit of the air (not alot). prob best to spoon it out. once you have got it all out, wet a spatula and smooth it all over. the water stops it from sticking to the spatula.

it depends on the size your making as to how long you have to cook it for. your egg white: sugar ratio looks good. generally its 1:2 in terms of volume. that works perfectly. i havent done alot of pavs with cornflour, i'm guessing it helps to stabilise it. make sure you sift (sp?) it in, and fold it in carefully.

good luck for #2