Building Client Portal -- 2

We need to build client portal for our existing as well as new clients wherein client can do following things. 1) Access His documents and share documents by drag and drop 2) Shared document can be viewed by assigned employee and automatic task will be created 3) Once employee has completed the task, invoice will be raised and emailed to client and copy in client portal as well. 4) Client can pay directly for the invoice from his login. Also Buttons for various services should be highlighted on client portal and separate payment link for each service. 5) Client can take appointment from client portal and notification to client as well as owner about the same. Meeting to be done on live more. 6) In client portal, Client can submit data for each service as per checklist uploaded by employee. 7) Client can also prepare invoice for their clients and upload purchase invoices and expense vouchers Python and Java Script experts to be preferred.