As you probably know, making Macarons is tough, especially making them at home. But it is possible as I have been able to create perfect macarons in my home kitchen, using Italian and french meringue. The Italian meringue always got me better results.
There are many reasons why your macarons don't come out like expected. First off, the meringue. It should be glossy and shiny like you say and also firm, but not too thick. When you take your whisk out of the meringue it should look like this:
The French say that when you take the whisk out of the meringue, it has to look a bit like a bird's beak, hence the way the meringue forms a soft peak slightly pointing downwards.
The consistency of the meringue mixed with the almond paste is very important. People often say it has to fall like a ribbon or like magma, but I always thought that is hard to imagine.
You can take a knife and cut through the batter. If it flows back immediately, it's ready. But let me tell you: One or two strokes too much with the spatula and the batter becomes unusable.
I always tried to make sure not to under-mix it. Then, every time making Macarons, I mixed it a tad more until I ended with an over-mixed batter one day. Since then I know how far I can go without destroying the better. Some people even count there strokes, maybe this helps you.
And one tip I can give you: The process of transferring the batter into the piping bag also 'mixes' the batter, so maybe don't go too far if you are unsure.
From my experience, making macarons with fan turned on always fails in my oven. For yours it could be different as every oven is different, but I only use top & bottom heat, 13 minutes at 150 °C in the middle of the oven.
When piping them it is really important to pipe them directly from the top (90 degree angle). Directly after piping them, I also tap against the bottom of the tray to remove any air bubbles.
You really have to experiment with the temperature and baking time. This process was really hard for me because even when the Macarons looked good from the outside, they could be hollow.
Although some sources say it's not necessary, I always wait a few minutes before baking my Macarons. When you touch them, they can be sticky but shouldn't stick to your finger. I never have tried baking them without resting.
Your first batch cracked, because the temperature was so high that the batter expanded too fast I believe.
What exactly do you mean with lopsided, do your Macarons look like this?
Or like this? (left one)
Maybe you should bake them longer at a lower temperature, you really have to experiment here, every oven is different. It took me a few weeks until I figured it out.
Also, make sure you let them rest enough.
Moisture could be a problem, but I don't think so. As long as they don't stick to your finger after resting and before baking, it always worked for me - even on rainy days.
So the thing I would try first is baking them without fan. If that fails, I would experiment with baking time and temperature.
Best Answer
I suspect you'll be fine. I often do simple unfilled baked meringue cookies and at least some of the recipes suggest letting them stand for several hours before baking. I've tried it both ways and notice little difference - but assuming your macaron cookie part includes a substantial amount of sugar, my evidence says it should be very stable for the course of a couple of hours.