You can split on a number of records, yes. But perhaps not in the way you’re thinking. There isn’t an option to split on the records at X records. Instead you need to set up grouping. You’d need a way to break up your data into multiple document sets.
So let’s say you want to split every 1000 records and your incoming data is an Excel file.
You’d first need to add a column to the data in Excel. In that column you’d add a number that only increments every 1000 lines. You could do this very simply with a formula. See here: https://www.extendoffice.com/documents/excel/3516-excel-increment-number-every-x-rows.html
Next, in Connect you’re going to need to set up your Grouping. Specifically you’re going to set Document Set Grouping based on your new column. This will make a new Document Set every time the value in that field changes. So, every 1000 rows you get a new value and therefore a new Document Set.
Finally, for the separation, you’d separate on Document Set instead of a sheet count.
As for your second question concerning Pipeline mode, I’m afraid due to the added functionality of being able to group and sort your data within Connect, this isn’t really possible. I think the closest you could do to simulate it would be to manually print in smaller batches. So print records 1-1000, then 1001 to 2000, etc.