Daz,
No you don't need to use the removal tool to upgrade. When you get the retail copy (irrespective of what iteration it is) you can just use the product key to renew the subscription. When a newer version is released you will be notified & given the chance to upgrade & Norton will clean up as it upgrades (This is all NIS I'm on about, not 360 or AV).
Re office software - I'm a die hard Office 2003 user as I've never liked or had the patience to like the "ribbon" that was introduced in Office 2007 - I'm currently using 2003 with Win 7. Office 2003 can be had for virtually nothing & although MS list it as being incompatible with Win 8, there seems to be plenty of users out there who don't have a problem. Food for thought if it's of any interest.