Originally Posted by kedarp
So please help.
I'll take that english may not be your first language, but this sounds to me like the wrong way to ask others help for something, as if the people on this forum is here only to answer you.
Please pay attention to how you write down your help requests
Regarding your first issue, have your tried running firefox as normal user inside a shell? What messages do you see? Please report them inside code tags.
To update firefox to the latest version I guess you should do it via apt, but nothing prevents you from extracting the tarball you downloaded inside a directory of your choice (even under your home folder) and run it from there.