Couldn't find any servicing intervals and costs. They seem to service them at the Nurburgring facility and there's a price list on their website but no R&T there, only the more expensive dampers there !
https://www.ohlins.eu/en/automotive/service/
Owners manual states the following Recommended service intervals,
Racing: Every 10 hours of operation, Maximum 20 hours of operation without service and oil change.
Regular street use: Every 30,000Km
Ohlins centre I bought mine from quoted me £95 + vat for a full rebuild/re-valve service.
Best mod ever.
Fuscobal, buy them,once you have got over the mental hurdle of the initial price, you wont regret it, they are that good, my advice is have a good bottle of ......(insert preferred beverage) first then get them ordered
Can't comment about track use as mine will never see a track,but for bumpy B road/country lane journeys around leafy Bucks it's the most composed car I have ever owned, The GTI is So much more relaxing to drive swiftly and ironically more safely now.