All exported dates and times are set to the time zone of your Shopify account. Open "General" on the Shopify settings page and you will find this option in the "Standards and formats" section:
To apply a filter on Orders to export only:
Please use the filter "Custom Term".
Please use a filter that decreased your lines less than 100. If you export products you could include only certain SKUs. If you export orders you could export only certain "Fulfillment states" or you could use a filter on a date field like "created at".
If you need to merge multiple columns to one column you can use the "mapping function".
Here is an example: You can merge "Address first line" with "Address second line".
First - select both fields:
Second - use the "mapping function":
If you need to calculate an additional field per order that has a certain value if the order contains certain products, then you can configure this usintg . You will have to add a custom column ("Layout tab"). You must set the "Export Mode" to "Compress" (you only want one line per order, but you need the order details compressed in this one line). You need to choose the order line detail that identfies the combined product - like the SKU. And you have to add a mapping ("Mappings tab") - like this one: