This last quote I worked on required the proposal to be uploaded to the agency's fancy new web server. Efficient and technologically savvy, right?
Wrong. Every vendor tried to upload their 2GB proposal to the server about 15 minutes before the deadline, crashing their server in the process. Thankfully no vendor got a quote in on time, so the deadline was extended three hours to let uploading finish. But I'm guessing if one or two got completed and the rest were still in HTTP limbo, they would have let those vendors fail.
Yes.
I've been involved with major IT delivery within the UK for GCHQ and the Home Office.
It sucked in a major amount of resource to get it done, and we still made sure that we submitted it a week early.
If there are further questions that your proposal didn't cover you can always answer them later. Miss the deadline, and there will never be questions.