1. Average £20-25k. People who can cope can make it up to around £50k depending on their skills and experience. Many fail to hit this mark. Some can go well beyond, but it is a small percentage. £100+ for senior developers.
2. Depends. Personally I'd say core programming is a great skill and very transferable, but depending on who you work for and the roles you want to aim for means this skill varies in need. If your good at 3D modelling, animation, art and texturing you can go that route. There is so many routes in the game industry so stick with what your good at, but make sure you know a decent amount of everything. Portfolio and passion is key. A degree in games technology isn't enough. You need to show you WANT the job, you need to be the guy who's making cool little tech demos or assets or whatever you do... and wants to show them off!
3. Urm, this depends where you live and what you want to do. AAA games in say the UK? Yes difficult. Europe, easier, America easier again. Getting anywhere notable in the AAA studios... harder. Like joining any big company at the bottom. Getting jobs in all the smaller independent studios is more accessible however usually very boring as many focus on social mobile apps, or games requested by other companies like franchise tie-in rubbish. The best bet is finding a group of people to make a game with and get it out, earn enough money to fund your next project! The thing is, its actually fairly easy to land a job in the industry, but most just aren't cut out for it... in the sense of structured development where deadlines are vital. Most people work better in smaller groups, get to express their input more, show their strengths and have a better chance at building a more robust portfolio or getting a well paid job!
The kicker is the crunch days. We get booted in the face to make sure the game is out on time with no problems. In the AAA market this is essential. Publishers are funding us and we need to make deadlines to make money. If we fail, we get nothing. We may even get shut down. Then no-one wants to employ junior developers from a failed studio... even though its not your fault. We spend months doing insane overtime for no extra pay, sleeping under our desks and living off local take-aways. There is however great satisfaction in releasing your work!
I may sound bitter here, but its a genuine issue. It is possible to have a very good career, but it all depends on your "break". If you join company 'A' you may fail misserably. If you join company 'B' you may have a nice run and have a good lifestyle. Join company 'C' however and you could find yourself being a bit of a celebrity.
Like many industries, there is the picturesque lifestyle and the reality lifestyle.