hi krishna,
you can save excel with password with read only protection, choose 'save as' option of your file, select the file type below you want, at tools slect general option where you can give your desire password with the option read only.
For your second query, select your entire sheet at first and check unlock from cell formats, then select those cells only you want to lock, again go the cell formats by right click of your mouse and click on check box 'lock cell' at protection tab,also click on check box 'hidden', ok, protect your sheet with password from cell format toolbar, now no one can see your formulas in formula bar.