Does Apple have another 40 years ahead of it, now that it has 40 behind it? As the world’s most valuable public company hit its anniversary last week, it’s the obvious question, in a world where the pace of technological change, enabled by globalization and the internet, is faster than ever. 

请问：

(1) now that it has 40 behind it 这句是什么意思？

(2) where 引导的是什么从句？