Yes, this is one of the most annoying limitations and it's been requested numerous times!
Look at the Files section in the Related tab of Projects. There you can either upload a file to Insightly directly or link to it in Google Drive/Dropbox/MS OneDrive. But this 'Files' section is not...
I have requested the same thing. It would be a tremendously useful feature.
The workaround is to select another Country (User Settings -> User Details -> Date Time Culture). Different countries have different date formats available.
Fully agree! Description and Product Code are absolutely critical to include in the quotation! And to open up the Quote Line Item for adding custom field would solve a lot of other issues.