Hello
I have over 28 years extensive experience with Filemaker Pro and have developed, deployed and maintained many instances from very large and complex down through to small more simple deployments, including a number of solutions with web based front ends (as recently as this week).
If you would like to send through some additional information on your project, including what kind of access you are looking from on the web side of things, as well as some further details on the spreadsheet you have created, we can discuss further and I can get back to you with a proposal and plan, along with a more accurate costings/timeline for completion.
Thank you
Darren