Let's go over the different technologies:
LCD means a liquid crystal display. Basically, there's a grid of millions of little cells containing a small amount of liquid crystal, placed in front of a backlight (traditionally some form of fluorescent light source, a cold cathode fluorescent light or CCFL). In response to electrical signals, the cells become more or less opaque, so that when they're opaque, the pixel is dark, and when they're transparent, the pixel is lit (each pixel is actually made up of three subpixels, each for one of the primary colors, but I'm oversimplifying).
In the past LCDs have had some disadvantages: the speed at which the crystals and therefore the pixels change were significantly slower than other technologies, resulting in a certain amount of "smearing" during fast action. The other problem is that because the screen was backlit and LCDs are not completely opaque, the contrast ratio (how dark the dark areas get, how light the light areas get) was pretty small. LCDs also had a relatively limited viewing angle--move too far off to one side or another and the image comes off dark or odd. In recent years, however, LCD technology has improved to the point of mitigating or eliminating those problems.
The TVs out there that are labeled "LED TVs" are actually just LCD TVs as well; the difference is that the backlight is provided by a set of LED lamps rather than a CCFL. The LEDs provide more consistent, "purer" light for better color, and their size means the manufacturers can do one of two things: Set many LEDs around the edge of the screen, making the TV significantly thinner; or set the LED's in a grid behind the screen. Setting them in a grid allows the TV to perform "local dimming," so that the LEDs themselves dim in the dark parts of an image and brighten up in light parts of the image, resulting in better contrast.
In plasma TVs the screen is made up of millions of little phosphors containing special gases that light up in response to electricity--think of them as millions of tiny little fluorescent or neon lights. Since there's no backlighting the images tended to be brighter and the contrast better, practically on par with the old CRT TVs. The disadvantages of the technology include being more power-guzzling, and the phenomenon known as burn-in: those phosphors don't last forever, and gradually use themselves up; if a particular image stays still on the screen for too long, they leave an impression on the screen that lasts a while (think of it as wearing down some pixels more than others).
Like with LCDs, over the years technology has improved so that these major problems of the past are significantly less of an issue, particularly for newer/fancier models.
Plasmas tend to be the cheaper of the three technologies in terms of screen size, but because of technological limitations you won't find any plasma screens smaller than 40". There's also a pervasive sense that plasma is older, on-the-way-out technology, so you'll find relatively fewer plasma models in stores. CCFL-backlit LCD's are also pretty cheap and come in smaller sizes, but above 40" they start being more expensive by the inch than plasma. LED TVs, the newest of the three technologies, is even more expensive.
When it comes to LCD and LED-LCD TVs you'll also find different varieties based largely on refresh rate--the speed at which the TV changes the picture. The cheaper LCDs will have a refresh rate of 60Hz, the standard for video in North America. The mid-high range ones will have a refresh rate of 120Hz, which enables the screens to display Blu-ray movies at the proper 24fps frame rate (on a 60Hz screen some judder is introduced, not noticeable if you're used to it but more obvious in comparison to a 24fps picture); most of those TVs will also have the notorious motion-smoothing feature which "tweens" the frames and makes 24fps movies look like Mexican soap operas (turn it off when watching movies). The top of the line LCD screens will be LED-lit, and have a refresh rate of 240Hz for even smoother motion. Most say that 240Hz is overkill, but 240Hz is needed for a flicker-flee application of the *next* tier up in HDTV technology: 3D HDTV sets.
So, to answer your questions:
1) Traditionally, because of the wear-and-tear-on-the-plasma-cells issue, the *impression* has been that Plasmas are short-lived. But with improvements in technology and the fact that the wear-and-tear stuff isn't really as bad as it seems--plasma TVs should last you at least a decade of regular use--it really doesn't matter. I think your TV set's longevity is more dependent on the brand and model of the TV, and whether they're really good when it comes to service.
2) "Living room with a few windows around" is pretty vague. If there are enough windows that you feel that glare may be an issue, a plasma TV may be more up your alley, but in most cases LCD's just as good as Plasma in this department.
3) See the stuff about plasmas. Yeah, it still happens with plasma TVs, but it's not as bad as most make it out to be.
4) Top tier brands are the big Japanese brands--Sony, Toshiba, Mitsubishi, Panasonic, Sharp, JVC. Second tier but still very good--and definitely worth considering if you're on a budget--are the Korean brands, Samsung and LG. Everything else falls below that, though I hear good things about Vizio (an American brand).
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