Varnish, FPC when there are lots of daily imports

Hi there, we have a site due to go live shortly but wondering about FPC vs Varnish etc. This site will have a full product import every night and then possibly partial imports during the day, up to every half hour. At :15 and :45 there will also be a stock import from the fulfillment centre. We are using FireBearStudio’s Import/Export module for these imports and they allow you to reindex after importing, which we thought we would need.

But am I right in thinking that every time there is an import there will be a full cache clean/flush/purge? In which case will Varnish offer any real improvement over the Magento FPC? If we installed a cache warmer would that be able to keep up at all? Just wondering what is the best way of approaching this.

ETA one further question re cache warmers. Our hosting providers have LiteSpeed set up so we installed the extension for it and set its crawler going – it took almost 5 hours to get through 3000 products. Is this indicative of other cache warmers?