Acc to chananya, a boats susceptibility to tumah depends whether it can be moved when loaded with stuff. If it can’t be moved by people but it could be moved with oxen, it could accept tumah.

For tumas midras- a zav/zava/nidah siting or lying on couch or chair. The item must be primarily designated for such a usage. If the item is primarily for something else and it happens to be that ppl often sit on it, it doesn’t accept midras. For example: a chest that opens form the top does not accept tumas midras but one that opens from the side would.

Earthenware materials are excluded from Tumas midras. We derive that the law of the couch is like the zav. Jsut as the zav can get pure by going to mikveh, so too midras applies only to items that be purified in mikveh. Earthenware cannot be toiveled and so it does not have midras.

Wooden kli without receptacle generally doesn’t accept tumah. If the kli is made to lie on, like a reed mat, it does accept tumah even though it has no receptacle. Since it has the capability for midras, it cns accept any tumah.

Wooden kli with a receptacle can be purified in mikveh. One without a receptacle cannot be purified in mikveh if it became tamei with midras. (It’s odd that they can accept the midras if they can’t be purified in light of the law that earthenware can’t get midras since it can’t be purified. But the gemara uses pesukim to show this law and says that at lest wood in general could be purified, even though though this specific scenario it can’t.

In a 6x6 tefach garden, one could have 5 different types of seeds and it still wouldn’t be kilayim. Four types around the perimeter and one seed in the middle of the garden