This is incorrect, there are two written forms of Chinese: traditional and simplified. As the names might hint, the more complex kanji characters are...simpler in the simplified form. Most new students are being taught simplified. Analogy: similar to the US not teaching cursive, some of the young generation cannot read all the traditional words as a result.
This is only partially correct. Only some of the characters are the same. The meanings also vary in many cases, so while you could read it, you may not get the correct meaning out of it. Analogy: we as English writers can read written French as it mostly uses the Roman alphabet. We can even read some Cyrillic because of alphabet overlap. But we don't get the meaning unless we actually know the language.
This isn't real different than any language. Just like in English there are a ton of words that are infrequently used or are olde Englische. We remove English words from the dictionary every year. Same goes in other languages.
Likely no, depending on the type of scroll this is. If it is a calligraphy artwork, depending on the artist style, it will barely be recognizable as a specific kanji symbol. Even if it wasn't heavily stylized, there are font and structure differences in words over time (just like we have different spellings of aluminium). There is a LOT of effort going in to OCR of Chinese calligraphy. I haven't seen a really good solution yet.
Look at this photo for example (sorry for picture of a screen, quickest way for me to post at moment). These are all the same kanji word. A kanji scroll is almost always some form of cursive, like the far right. And that cursive is not a standard, unlike English cursive - calligraphy cursive is an art and depends on each writer. There are very famous historical calligraphy artists who are known for a specific way they write one symbol.