Product Research - Human Resources software

I am looking for a someone knowledgeable in the Human Resources software market, to suggest one of more pieces of web based (cloud) software to help with the re-organisation of many hundreds of people in a mid-size organisation. It must be web based, be able to support the loading/importing of Microsoft Excel data (600+ people, one person per row, with large number (30+) pieces of data per person). It must then be able to manipulate that data via a simple browser interface (so limited IT skills are needed), and then export/output that data into a final Excel sheet. It must be able to record every change/transaction made (date stamped) for auditing purposes. It must not require a software application to be loaded onto a PC (100% web based). It must have good security (passwords etc), to prevent non approved users logging in. It needs to be simple to use. I must be able to buy a copy online (not need special bespoke software licensing and complex contracts needing lawyers to review).