How to boot installed system from a usb disk? (Warning: newbie)

[Ottavio Caruso <ottavio2006-usenet2012%yahoo.com@localhost>]

Hello and first post here.

Coming from the Linux world (Slackware lately) I find the Netbsd
documentation a bit terse. I have researched this topic on both the
Netbsd online guide and the install.html file but I couldn't find an
answer.

My goal is to install the 64bit port from a usb image onto a local
partition of my drive (currently Win 7 Home) but I don't want to
install the bootloader yet. I want to be able to boot from a usb disk
(either the installation one or a different one). My questions are:

1) At the stage "Installing the boot selector":
http://www.netbsd.org/docs/guide/en/chap-exinst.html#exinst-partitions

should I select "no"?

2) If so, how would I then boot the installed system? Should I drop to
command line prompt and type some commands?

3) How would one normally create a USB boot rescue disk on Netbsd?

4) When I change my mind and install the bootselector on the hard
drive, how would I make sure it wouldn't overwrite the Windows boot
sector?

Many thanks in advance.

-- 
Ottavio