Bicycle carriage & few general questions

Hi there,

I'm looking to buy either a 21 day JR pass or a few regional passes. Few questions...

1. Is it possible to buy the JR pass online but collect in Japan since I'm currently travelling and so have no fixed address. (I'll be arriving to Fukuoka by ferry from Busan).

2. I understand some trains (night trains especially) require some advance booking due to selling out but in general am I able to jump on & off trains as I please without advance booking?

3. I will be travelling with a bicycle. How does taking a bicycle on the JR work? Does it need to be in a travel box/bag. Does it require advance booking? Is there a particular carriage to carry over-sized luggage?

4. As I understand the JR pass doesn't cover the individual city metro networks. Can you confirm this?

5. Do you have a link to a list of authorised agents outside Japan where I can buy the JR pass from?

Thanks in advance