Hey man.
1: Yes, it\'s possible. phpMyAdmin will let you import and export entire databases quite easily.
2: Aliases are just that. They\'re mainly used to help keep code cleaner and to prevent any data from being overwritten. If you performed a join on two tables, for instance, and they both had an ID field and you needed to select them BOTH, you could give the first ID field an alias so that it wouldn\'t be overwritten by the second ID field. It works for both field names and table names. Example:
[php:1:265a818570]$sql = \"SELECT table1.id AS id1, table2.id AS id2 FROM some_really_long_table_name_omfg AS table1 LEFT OUTER JOIN some_even_longer_table_name_wtf AS table2 ON table1.id = table2.id WHERE id1 = \'$id\'\"[/php:1:265a818570]
The key is the AS command. The general syntax is [table|table.field|field] AS [alias]. NOTE: You can only use field aliases in a WHERE clause (notice how I didn\'t use \'table1.id\' instead of just \'id1\' in the query). Table aliases will only give you an error.
3: Unsigned is a property of integer field types. It simply means that they cannot have negative values. This is good to have with ID fields.
4: I\'m not sure I understand you. Did the script tell you to grant the user a MySQL account with read-only access or did it simply say that it wouldn\'t let the user alter anything in the database when it is run? If the latter is the case, then yeah, it probably meant the user only has access to the SELECT command.
5: Nope, the OS doesn\'t really matter. Everything is stored the same way regardless of operating environment.