Right no 1.
I think the best advice here would be to create a userform for your password box,
With this you can put in a text box that will let you select a password character such as *, and you can use any functionallity you like here, all your Auto_Open event will do would be to load and show an instance of this userform,
The user form itself can be set up like you would see any other password screen probably with a name box and a password box and a couple of buttons dependant on action, Ok and Cancel, I don't think you can hide the characters in code but instead you should password protect your code.
you can also use Option Compare Text at the top of the Userforms Class Module this lets "AAA" = "aaa"
#2
if you password protect your sheet initally you can use
Sheet1.Unprotect "MyPassword"
and
Sheet1.Protect "MyPassword"
and finaly some notes about your code
this
Code:
Dim myRange As Range
For Each myRange In Range("B6:N30")
myRange.Value = ""
Next
can be replaced by Range("B6:N30").Clear
i always like to put the word Call before any module calls it just helps show exactly what your doing if you are just skimming over your code,
finally it might be helpful to add coments to your code just to let you know what's happening, this helps when you have to go back into your code to change anything as it makes it easier to see what's going on(I know im guilty of this too)
HTH
Dave