iTunes Match syncs and displays of your playlists on all the computers/iOS devices (up to 10 devices in total) on which you've enabled iTunes Match. Well, many of them—if you have playlists that contain podcasts, videos, or music videos, they won't sync (even 1000 songs and one music video, say). But all your music-only playlists should be available on different computers and portable devices.
I noticed that there are many songs in my iTunes library that are sold on the iTunes Store, but that have been "uploaded." I noticed that some tracks had different spellings, and I changed mine. I tried to update iTunes Match, but I still have the same amount of uploaded tracks.
iTunes Match does not look at the tags in your music files. You could call David Bowie's "Heroes" something like "Four Score and Seven Years Ago," and iTunes Match will ignore the title and merely look at the music, creating an acoustic fingerprint that it uses to match against its catalog. So even if you change tags on your own—something I often do with classical music—this won't affect whether or not they match. Also, if you match songs whose tags are incorrect, iTunes won't fix them for you.
I spent a lot of time adding CDs to my iTunes library in either WAV or Apple Lossless formats. If I understand correctly, I will lose this quality level if I use iTunes Match. Is this correct?
Yes and no. iTunes Match won't alter the songs in your library unless you choose to replace them. If a lossless track has been matched and you delete your master file, the version you re-download from iTunes will be 256 kbps. And if you download that track on another computer or an iOS device, it will similarly be 256 kbps. Unmatched lossless audio files that are uploaded get transcoded to a 256-kbps AAC file first, but again don't affect your originals. In most cases, however, 256-kbps AAC files are fine for portable devices—taking into consideration storage space and the headphones or speakers you'll be listening through. So you might want to use iTunes Match to provide music to, say, an iPhone, but still use your iTunes library on your Mac when you listen via a stereo.