Looking to buy first Jaguar

Hi all, newbie here. 

Having sold my Porsche 911 I'm looking to buy my first Jaguar. I'm a complete petrol head with a car history that includes a 911, Boxster S soft top, Porsche 968, BMW, `Saab 95 turbo, VXR8 etc etc. 

Budget is around 30K and as I'm into performance cars I am potentially looking at an XJ-R. There seem to be a few on the market within my price range, including LWB versions. I would only buy something with a complete service history file, bundles of invoices and a stamped service book. So I'd like to seek advice please:

Running costs. I'd look to use an independent specialist for servicing. How expensive are these cars to run?

Known problems. What should I look out for in terms of known problems and check that these have been fixed before purchase?

What are these cars like to,live with long term, as in a year or more (I change my cars every 18 months or so). 

'Anything else I should consider?

All help and comments appreciated. 

TIA Andrew.