I'm slightly worried about the size of the A350. Its more along the lines of the Boeing 777. Aer Lingus ordered quite a number of A350's which will seem to give them a big capacity boost over the A330-200/300. That will work in the summer but the winter they will struggle to fill them, as well as finding routes for the fleet. They only operate 8 A330s at the moment and plan to dispose of one more as the fleet is still too big.
Yup, the A350XWB has been growing steadily since it was announced. The A350-900 is roughly the similar to the 777-200ER, while the A350-1000 will come closer to the 777-300A.
The A350-1000 has LOTS of problems, mainly coming down to the engine. The RR Trent XWB is too small, and RR is reluctant to design a new engine only for the -1000. This will effectively leave most of the market open for the 777-300ER.
The A350-800 is something of an odd-ball, and will ultimately prove to be a rather short and heavy plane with high operating costs. It is simply too fat. It will be slightly smaller than the A330-300 and 787-9. The only real advantage it will have over the 787-9 is that it will have a greater range, and commonality with the other A350 variants.
Aer Lingus should probably have gone for the 787 family instead. The 787-8 is the same size as the A330-200 and the 787-9 is the same size as the A330-300.