Thanks for the review and with respect to issues:

#1. Downloaded files being saved like download(1) download(2) etc..

Not reproducible.
Could you check on this thread - it requires some plugins to be removed - https://support.mozilla.org/en-US/questions/1200035
and let me know if it solves the issue. If it persists you can let me know the webpage which has this issue and if you are on Windows?

#2. Downloads not being completed - pending downloads

Throttling should help. Will soon get this addressed in next version.