SSIS log file behavior, minor annoyance but wierd

I am playing with the various ways you can configure the file connection manager for SSIS logging and I'm trying to understand the following behavior in the way the file is created. I'm also making some observations which I would like to confirm from other users.

In the connection manager for the SSIS log, under usage type, I played with both "Create file" and "Existing file" options.
What's the difference between the two?

"Create file" option

As the name suggests, if the file isn't there, it creates a new one. I also thought that it would delete any previous logs and create a new log each time the package is executed, but it seems new logs are appended to the existing file. No big deal.

"Existing file" option

It seems to behave just like "Create file" option, except that during design time, you need to have the file in the location specified, so that you can "OK" out of the connection manager editor. After you "OK" out of of the editor, it seems you can delete the file, and the package won't error. Contrary to the name "Exisiting file" option, it still creates a new file, if it doesn't exist.

Next try these steps.
So that you are doing exactly what I did, hard code the connection string (the file name and location) in the connection manager editor, as opposed to using an expression to set the connection string

(1) Choose "Existing file" option.
(2) Place an empty file in the specified location.
(3) Run the package and see the content of the log. Does your log file have a header? Mine doesn't.
(4) Now, delete the log file. As I observed and noted above, despite what the option name suggests, the package will create the log file. Now look at the content. Does your log have a header? If it behaved like mine, yours will have a header now.

Minor stuff, but wierd.

There's one more wierd behavior, but I don't want to over load the thread. I'm hoping some experienced SSIS developers have noticed the above and also perhaps noticed this other behavior at which point we can discuss further. The other wierd behavior happens when you use a date/time based expression to specify the connection manager, ie, make it so that the file name is dynamically created to incorporate some kind of a time stamp.