Massive news, To attract a airline in the calibre of Qatar to CWL cannot be underestimated, The benefits to both the airport, the city of Cardiff and the country as a whole is hugely beneficial in what I'd say is a huge turning point, The potential use of the service for the catchments of both Wales, the Midlands and the wealthy southwest catchment means I'd be stunned if this wasn't a success like you've said Local, It's not only the airport side of things, it's the business that could be bought into the country, investment opportunities, Job creation, the positive effect on current CWL services, inbound tourism, additional revenue through the airport.
There is a could of interesting points in regards to a LH carrier:
Airbridges - it's a well known fact that the airbridges at CWL are not completely functional in the sense of movement since being placed on concrete blocks to raise many years ago, Qatar services wouldn't have a problem using either gate 7 or 10 providing on the aircraft type:
A332,A333, B788, B789 could use Gate 7
A320, A321 could use Gate 10
However it is worth pointing out that if Qatar did want the airbridge fully manoeuvrable so the middle door is used so economy passengers don't walk through the Business ( FC cabin on some aircraft also) then this would require work in the upcoming winter, The waiting areas aren't really ideal next to either of the gates, 7 is essentially a long corridor with a few chairs put in the middle which is also used for flights using 3 and 8 and 10 has a sort of a waiting area off the corridor which is pretty small, I imagine some work will be done the make it suitable for the airline, will be intriguing to see what happens with the airport infrastructure with seemingly the check in area needing extending with a Qatar focused area with Premium, the area towards the BA maintenance seems the most likely course of action, especially with expanding SH carriers something will need to be done about it sooner rather than later, Could Qatar open up there own lounge potentially on floor 2 ? Will the current one be extended for a larger area; lots of work to be done but I'm pretty sure the airport have the plans already in the place, with work to start after the busy summer period.
Very, very exciting times, coupled with the fact that a potential SH carrier expansion is talked about for next summer, these are exciting times, along with champions league final and now this very much puts Wales and Cardiff on the map, hopefully it's the start of many new exciting developments over the next year or so !