Length of order history

Will
Customers->Orders

only show 1 page even if you have 1000 orders ?
If so wouldn't it be convenient if you could turn pages on filter it so you only see orders for a specific month?
Futher more I don't think it should be possible to delete an order unless it is several years old or if it's status never has reach some level like delivered

No. It shows 20 orders per page. There are already a number of filters that you can apply (top left) though date isn't one of them, and a search facility.

Whether you choose to delete recent orders or not, is your choice as a store owners. Other store owners may have legitimate reasons for deleting them (e.g. duplicate orders that they have cancelled) and choose to operate a different policy. Zen Cart doesn't make a judgement on this, allowing store owners to choose for themselves.

I asked this before but this seems like the right place as it fits.

If you delete a customer's order in Admin does it affect their order history for their accounts?

Beth-Katherine