Beginner's questions

I'm a novice in COBOL, and I've got a couple of questions.

1. Consider a CCB entry:
05  FIELD PIC S999V99.
what will be size of data? From the manual it looks like the size should be 
5, but how can I post negative values?

2. 05  FIELD PIC S999V99 USAGE DISPLAY.
The same - what will be the size and how to distinguish +12345 and -12345.

3. 05  FIELD PIC 99999CR.
Do CR/DB items have any representation in data? Please give examples of the 
data valid for this PIC clause.

4. 05  FIELD PIC 99999B.
Does B have any influence on data? Please give examples.

5. What is the usage of N and G symbols, could you please give examples of C
CB entry and corresponding data?

In all the questions under 'data' I mean 'unedited' data which is present in
 the source data file.

Thanks in advance.