32" seems to be where lcd and plasma overlap, with plasma being cheaper for larger sizes. I think alot of the differences between the 2 are now gone, lcd can have a narrower viewing angle than plasma (but generally not a problem now), similarly older plasmas were vunerable to screen burn, but less of a problem now. I find lcd screens "sharper" and plasma "warmer", if that helps

Best to go with the picture you like best your self.
From a size point of view 32" may be too small to notice any difference, I've heard it said it's only at 42" you start to notice the extra detail. Again go with what your eyes tell you.
A normal tv picture is about 500 lines, HD is 768, 1080 or higher. (& either i - interlaced or p - progressive, progressive being better).
The problem with HD is sources, what will you watch. Sky HD is coming out now, not sure what will be available or the cost. The xbox 360 is HD compatible. Some newer DVD players will 'upscale' a picture to HD, but current DVDs are not HD. Competing formats are only now emerging and it's not clear how may films will be available (& at what cost).