"...When I click the Text Button there is NO Text menu appears as explained in the Manual..."Perhaps you have clicked the wrong button. In NotePad there are actually two different tools for entering text:
The Lyrics Tool (icon: feather and ink)
- for entering lyrics attached to notes (or for entering chord symbols, since NotePad doesn't have Finale's Chord Tool). You can also use the Lyrics Tool for entering Right Stick - Left Stick notation (R - L) in a snare drum part.
The Text Tool (icon: capital A)
- for entering text
The Text menu only appears when you are in the Text Tool.
"...I just want to enter the notes by looking at the Printed music notation in Finale to convert it to .mus files. For this requirement
1) Is Notepad or Notepad Plus is enough?
2) Or I should go for Printmusic?..."
The .mus format is the same format used by all the applications in the Finale family:
Finale, Allegro, Finale Guitar, PrintMusic!, NotePad Plus, NotePad.
In Other Words: Just enter the notes in NotePad, using the Simple Entry Tool. The document you create in NotePad will be a .mus file, readable by Finale. No file conversion needed!
"...Also how the scanning the notations from the printed sheet or importing the notations (from a .tif file) works? Are they easy and if I can import the notations to somewhat original(with less errors or variations) can I correct them after I scan/import?..."
For scanning you will need at least PrintMusic! - neither NotePad nor NotePad Plus can import scans.
Scanning, however, has its limitations. You will have to do some editing afterwards, partially because not all elements in notation will be recognized (e. g. lyrics, articulation marks, hairpins, repeat barlines), and partially because you will have to clean up and correct errors after conversion (yes, you can correct them after scan/import). The better the original, the better the recognition accuracy. Don't even think about scanning handwritten manuscripts.
In some cases you will find it faster to simply re-enter the music instead.
Peter