1, Make buy and sell order limits the same.

Currently the max sell order size is 10 times of the buy order. Like you can put up 10k ore to sell, and 1k to buy. 100armor to sell but 10 to buy.

There is no legit reason to have the buy smaller, but it's unhealthy for the market while also annoing to buy items in small amounts.

2, Increase the max order size.

The warehouse size is 5k LT at the start (and can be overweight up to 5k), that's why some items have the limit they have currently(example armors, food), so the max sell amount is 5k LT.

That's ok, but some items have much smaller limit, like black stones, and crafting materials. Making buying/selling them is time consuming.

Make it, so every item have the max order size equal to 5000LT. That way you would stil not have issues due to warehouse limit, but it would be easier to sell/buy.

Even without altering the Pre order amount.  Allow someone to purchase Up to their current max Warewhouse Weight including the overstack ammount in a quanity only limited by warehouse capacity as long as it's in stock, however only allow so much for preorder.  Same goes for listing, you can list any amount as long as there is an order for it and you can put that amount in your warehouse, however you can not list an amount over the current limit if there are no orders.

IE.

If there are 100,000 weeds on the market and my warehouse can hold them all I should be able to buy 100,000 weeds in one go, but if there are no weeds on the market and you can only list 10,000 then I should only be able to Pre Order 1,000 at a time.  Conversely if there are 100,000 weeds preordered on the market I should be able to list all 100,000 Plus the 10,000 that I can normally list for a total of of 110,000 listed in one go.