Can someone answer my questions , please

Hi,
1) Which RFC should I follow in case of file URIs 2396 or 1738 ?
2) About the escaping of ':' separator of the drive letter.
I understood there is no need to escape the ":". But is 
"<file:///e%3a/xxx.pdf>file:///e%3a/xxx.<file:///e%3a/xxx.pdf>pdf" also 
valid ?
3) Relative file URIs : Is it equivalent to use "./foo.pdf" or 
"<file:/./foo.pdf>file:/./foo.<file:/./foo.pdf>pdf" or 
"<file:///./foo.pdf>file:///./foo.<file:///./foo.pdf>pdf" ?
Are the last 2 examples which uses scheme name and relative form , invalid 
URIs ?

Thanks in advance
Israel