I took a look at the list and I have to say the job outlooks must vary considerably by primary skill. I would say that if, in the current market, finding a senior development job is a challenge you are doing something horribly wrong.
In my case I am a senior JavaScript developer who doesn't like the straightjacket stupidity that is popular large monolithic frameworks. The demand for this skill is stupid ridiculous. If you want a new job simply put your resume online in one of those job boards like CareerBuilder or Monster. Within 2 weeks the recruiters will discover it and I expect to get 6-8 responses eagerly pushing me into interviews once my availability is "discovered". After those initial responses I might get another 10 or so serious asks for my time.
Most people who do web work, in my experience, actually cannot code. If you are a strong coder the interviews are largely a meet and greet, because you probably have a strong answer for everything in your comfort zone and immediately shut down questions about areas where you are weak.
You have to consider that web jobs are generally considered low barrier to entry and so half the people that apply are grossly under-qualified and many that are qualified are just learning to code and incredibly far away from "senior" level. As a senior, an actual senior, expect to enter the job jumping potholes and dodging landmines from the incompetent code already in place. This doesn't mean that I think highly of myself, but rather many companies don't know how to develop or hire strong web developers yet, in the meantime, they still expect work to get done somehow like a mistake mosaic.
As far as salary goes I have generally made more time I have gone somewhere else. Because the demand for senior web developers is ridiculous stupid many employers suspect if you are interviewing with them then you are probably actively interviewing with 3 or 4 other prospective employers, and so if they believe you are a competent senior there is a rushed hurry to get a hiring decision back to you as soon as possibly, often in the same day you interviewed. With that rush comes high salary offerings, which I guess is an effort to outbid the suspected competition.
If you are interviewing in the corporate world and actually are at the senior level age is irrelevant and the preference skews a bit older. Nobody is going to believe you are actually an awesome senior developer if you are under 24 years old unless you are a brilliant child prodigy who has been inventing new software techniques for the last 8 years. I am on my way out of my thirties and my age has not hindered any demand for me.
As far as interviews go what has done me well is honesty. This means telling prospective employers things that might make them throw up in their mouths. I don't like large blunted frameworks and so I prefer to get much of the nonsense out of the way early on. If the disdain for the safety scissors is a deal breaker then don't waste my time and I won't waste yours. Since the demand for seniors is ridiculously stupid I am fortunate to be less afraid of being so blunt and immediately honest.