Kryptoe, hope this helps:
1- Since Bitcoin is the first blockchain cryptocurrency, it has set the stage for all others. As such, the value of subsequent coins or tokens is understood in terms of Bitcoin the same way the U.S. dollar is seen as the world's reserve currency. BTC is the base medium of exchange and all other coins can be converted to it and purchased with it.

2- I wouldn't say they're all in competition with BTC, many of the biggest ones maybe, but each is trying to set themselves apart from the other alts based on how similar to BTC or innovative they are.