I can try to help, but I'm not familiar at all the the Toshiba PLC. Most japanese PLC systems that I have used in the past use an unstructured flat memory style and the user blocks off registers as necessary for integer, bits and floating point reals. You mention displaying a pressure so I would assume floating point which would mean several registers. From your text, I would also assume that the XW000 data register is your raw value from the pressure input and the D0100 is your scaled value. Not sure tho. You will have to correct me if my assumptions are incorrect.
I would have to guess at using D for your tag with my assumptions. Generally once you select a data source and data item, the RedLion guides you through the following selections. I would suspect you have a single field to input information and would expect there to be a 0100 entered into it.
Assuming your D0100 register is used as a real in your program I would expect Real as a Real - possibly Word as a Real. That should be Toshibaese...
The next selection is easier as you are interested in one element not an array of elements. So pick One Item.
I would not expect that you need to do any word manipulation, but that is dependent on how the Toshiba offers up its data. Start with none and you will have to break out the Toshiba book and understand their handling of data in more depth.
Once again I assume you have configured your data as a real in the PLC so Floating Point would be the correct tag designation.
For display of your pressure, read only is acceptable.
The formatting is really for your display elements. You can choose to format at the tag level or the display element level. If I am going to add a tag I generally format at the tag level. To display a pressure you will want to choose numeric and configure how many places before and after the decimal place you want.