LuL, LB and anyone else here who may be interested. It is imperative to take instruction from a competent Rav in pesach matters. Some of the things said here are not accepted by everyone. I’ll give a few examples.
Finding chametz on pesach – It is not simple just to burn it. You are thereby showing ownership over it. If it is sold, it is no longer yours. You would have to ask your Rav if you can destroy it. It will depend how much it is, how edible it is and some other things.
Selling your house – Actually selling? Or just renting to the goy? Selling implies a deed of sale and lawyers and everything. Selling chometz is not a joke, it has to be a legal sale. If you look on YouTube for “gateshead rav chametz”, you can watch Rav Zimmerman conduct the sale before and purchase after pesach of the chometz from a real Geordie (as opposed to a Geordie613). He even mentions his dislike of Marmite.
Chometz of a certain size – Keeping chometz of a certain size should not be allowed. It may be technically permitted, but we don’t because it may come to be eaten.
Cosmetics – Some are very particular to go through their whole cosmetics stock checking each item. Others hold, that they are no longer edible for a dog, and therefore not considered chometz.
Kitniyos – a huge subject, and dependent very much on family and local custom.
This is just a small example of questions that come up, and you will find many conflicting opinions. Your LOR in your LOS or LOBH will probably be giving a series of shiurim in the run up to Pesach about all these questions and lots lots more. As learned and experienced as some of us in the CR may be, we are at the end of the day anonymous people with laptops, PCs or smartphones. Nothing can or should replace your reliable competent and caring Rav.