Question Banks in Storyline 360

Hello Heroes! 

Our team has been asked to create an assessment based on a total of 274 questions (!) 

We'll be importing an Excel spreadsheet of questions into Storyline 360 to create one (or more) question banks. Although we have plenty of experience w/ Storyline. this is our first time working with question banks. 

Here are our questions:

• In your experience, is it easier/better/faster to create 1 or multiple question banks? (In our case, there would only be 2 if we choose to create multiple banks). As I see it, 1 bank keeps everything together, but creating the draws from such a large list of questions could be tedious and might be prone to (my) human error.
• Is it possible to import multiple Excel spreadsheets, or just one? We currently have questions separated by topic, so we thought about importing 2 separate lists. The only info I've found close to this question says, "Only questions in the first worksheet (tab) of your Excel workbook will be imported. Additional worksheets will be ignored." 

Thanks!