I sympathize with your sentiment regarding MS EXCEL but, ultimately, LiveCycle (and the complex coding requirements) is the only way to deliver solutions that can't be messed up by other people.
I still struggle with 'for' loops - they're not nearly as intuitive as 'if, else' constructs BUT mastering both of these constructs gives you 95% of the functionality you were able to squeeze out of EXCEL.
Articles/examples by BRINKMAN (google FormFeed) and NIALL (google Assure Dynamics) helped me a lot in improving my command of LiveCycle Designer.
Great news - progress is very much about incremental steps -- my understanding is little more than a function of the knowledge of others. Niall has been very generous in providing so many 'worked examples' for LC Designer practioners - visit his website, download some forms and your capabilities will expand massively !!
I should have probably mentioned that my programming skills are only that which I have had to learn for basic forms, so this is a challenge for me . http://adobe.ly/1K5ykgK. The item formula that I am stuck on is in trying to resolve Step 3 of the form. I wish it worked like Excel. That was much easier.
The "Scripting Reference" under LiveCycle's Help menu bar item has more information about the FormCalc statements.
Since this is custom scripting you need establish the link to the field objects and then use the "value" property to get the user input for the field.