I have 7+ years of experience in SharePoint/InfoPath/SSRS. Am working for MNC as Sr. Software Developer. we create the form to store the data in SharePoint. but its going to be the same if you are planning to store at some other location. based on submission, we can create workflows for approval as well
Coming to your Project.., As you said, you have 26 fields. So, its impossible to create infopath form in 2-3 hours. though you can design it but at the backend , you have to write rules, have to create data connections to pull the data, have to check whether it will overwrite your existing forms or not, etc..,
To create your project, I will quote 15 hours (atleast). Thanks for understanding.