Allowances depend on fleet but aren't that great - c£2.50 per hour, payable for 24 hours a day if you are away, eg. on long haul. Very few stops on the short haul fleet. There are now two salary scales, the Senior FO scale you'd probably take home around £2000+ per month depending on allowances.
The company does have ID90 agreements and similar with many of the scheduleds and also arrangements with other charterers.
There are also concessions available with the company for its own holidays although there are restrictions.
The list of those eligible for command seems to get longer and longer...