Nice colour. There is an Iconic Facebook group as well. On the audio front, it depends what you want, i had audio on my 2014 bike and never used it, but that is a personal thing.
Things to look out for, make sure the exhaust flap is functioning, its a £1200 repair if it isn't so I would check the warranty covers this as the extended BMW Insured warranty doesn't. There are plenty of discussions on here if you search about the exhaust flap issues.
If there is any corrosion, I would defiantly have any corrosion seen too, if they refuse, buy another bike, there are plenty around without corrosion. Also the Iconic is a nice paint job with a few extras, but it isn't a factory painted option, they were all painted in the UK by 8 Ball, so although really nice, it is not a BMW global limited edition.