Create an Database Web App

I am looking to create a searchable client database. I already have a very large data source in Google Sheets and an App was already created for me by another freelancer. However, I want to start over and create because the other App could be improved in several areas. First, let me tell you how my current App works: 1) A user/employee inputs a client record through a Google Form. (See the attached file "1 - Form") 2) Then, the record generated by the form is automatically placed into a spreadsheet. (See the attached file "2 - Spreadsheet") 3) Next, the spreadsheet provides info for the database, which is a searchable front-end app.(See the attached file "3 - App Database") 4) The app can then display the individual records for the user/employee to see. (See the attached file "4 - Client Record") 5) The app also provides a case checklist that can be used to keep track of certain facts relating to each client/record. (See the attached file "5 - Task Checklist") Secondly, here are the areas that need improvement in my current App: A) I cannot add additional parameters to the record without contacting the developer. For instance, if I wanted to add "client's fax number" to each record, I would not be able to do that. B) I do not like the look of the current App. It is not very pleasing to the eye. It is not easy to find information on a screen. C) I want to be able to create a way to access a shared Dropbox folder from within a record. I would like for there to be a button or link from within the record ("4 - Client Record") that takes me to the corresponding Dropbox folder. IF YOU ARE INTERESTED IN THIS PROJECT, please advise how you would address the issues I have discussed. I will not consider you if you post a generic response to my job. That is only fair and sensible. Thank you very much in advance.