Hi,
The history of the order only records when the order was changed, and by who and for what reason. It doesn't record what emails were sent.
If you want to check that, you need to go in the menu Customers>Emails history.
There, you can filter with the order number to get a list of the emails sent for that order and you'll see what was sent.
When you add a product to an order after selecting it from the products listing, it will automatically provide you the price and the taxes. But if you add a product without selecting it, then it's up to you to enter the price and taxes you want. So make sure you use the adequate button on the top right corner of the products listing.
Finally, note that all the prices are stored with 5 decimals in the database. However, when displayed on the frontend, invoice, email notifications,etc they are rounded based on the settings of the currency. That's because for example, sometimes you need to define a price without taxes with more decimals so that when the tax is calculated, the system can end up on the exact rounded amount you wish to display on the frontend.