First of all a little friendly advice...
Its never a good idea to
blame your inability to use an application
as being a 'bug' with the software...
...I s it a bug in photoshop...
...especially when your opening line is.....
hi am new to photoshop...
Now, on with the problem.
1. "...unwanted stroke around the shape..."
As Nathaniel-WoLvEz has already pointed out the 'stroke' option is disabled via the 'stroke' icon......BUT.....if you then change the stroke 'thickness' or its 'Style' the stroke option is automatically enabled again.
PS assumes that if you change the stroke thickness you MUST want to apply a stroke......this is not always the case but it IS logical....you wouldn't need to change the stroke thickness if its disabled, whats the point?.
So.....when defining a 'Shape' always check that these options are correct before continuing.
Now, I'll get off my soap-box and continue.
I'm not sure what the attached psd file is.
It doesn't have any paths nor shapes which relate to the problem you are having. There is only one layer with a black rectangle, ('Rectangle 1'), with some lines protruding from it around its edge. (As in your attached image).
Where is the path you speak of?
2. "...is keep in going to Grayscale..."
Your attached image shows 2 open documents.....one as
RGB 8bit and the other as Greyscale 8bit.
This is a USER choice, PS will not just change the mode on its own.
Check your settings for a 'new document' and make sure that the
Color Mode is set to RGB....
This is all I can think of as to why that second document would be Greyscale 8bit.
Regards.
MrTom.