The two basic input requirements are Stocks and Parts. Every Stock requires an ID (this has to be unique), Size (Length) and Quantity. Similarly parts require an ID (has to be unique), Size (Length) and Quantity.
The ID of the stocks and parts can be made of any alphanumeric characters. Only keep in mind that the ID's have to be unique.
Yes, you can do a lot more than that using the Customize Header option.
You can select your preferred units using the TOOLS->Unit Settings Menu.
Check if the "Allow Offcut" setting is ON. Probably, the remaining piece is larger than the minimum offcut size. In such a case the remaining piece is NOT considered as waste.
Go to the View->Toolbar menu, and ensure that the toolbar is checked.
Combining of parts means adding parts of same length, Material and cut allowance in a single entry. For more help see combine parts
This is a warning message. The software tries to minimize the cost of all the layouts. Therefore it will try to use the stocks in such a manner, that the overall cost of all the stocks utilized is minimum. The above message means, that PLUS-1D has found that one of your stocks is much cheaper than the others. This could be an data entry error, so the package giving you a warning message, so that you can double check the data.
You can have the cost of the powder coating material in the RTF output.