There is no difference between the alter in the Bais Hamikdash or in Shiloh except that by Shiloh you could eat kodshim or maaaser sheni as long as you could see the alter whereas in yerushalayim you could eat them in the whole yerushalayim. In both places kodshei kodshim like a korban Chatas can only be eaten within the walls .

After Shiloh was destroyed you could have a private bamah whereas after Yerushalayim was destroyed no bamah was permitted.

Megila 2:1

You cannot read the megila backwards. If you read it by heart or in any other language that you don’t understand, you have not fulfilled your obligation. However to somebody who knows a foreign language, you can read it in another language. Even if you don’t know Hebrew you have fulfilled your obligation if you hear it in Hebrew.