Short answers:

1. No.
2. No
3. (Usually) the latter
4. You don't generally "call" a variable, but if you mean can you make use of it, yes
5. Several

This series of questions practically begs for a near-complete Perl tutorial. It seems that's what you need. So please read some documentation; a book; or examples of working code here in the Monastery, rather than jumping to unwarranted conclusions.

I withdraw this post and replace with: You were right. Reading a basic tutorial and paying attention to chomp would help. Sorry I'm not used to /n being auto included. Usually I have to tell the program to start a new line.

chomp() will remove the end of line character(s).
On Windows these will be 0xOA, 0x0D.
On Unix this just 0x0D.

Perl is permissive about what it receives for a text line. chomp() will remove the end-of-line character(s) - might be 1 or might be 2 bytes.

When Perl writes a line: print "something\n"; , that \n may be one or two characters depending upon the OS and the context (network communication uses 0xOA, 0x0D - no matter what the OS) - but Perl knows about this and does the "right thing".

If I transfer a file from Windows to Unix, sometimes I need to do something like this to "convert" the file:

while (<STDIN>)
{
   chomp;         #remove line endings
   print "$_\n";  #write this OS's line ending
}
[download]

"chomp()" is your friend as opposed to "chop()". chop() is seldom used.
The 'C' functions that read lines do the "chomp" automatically for you.
In Perl you have to do this yourself.