It starts off really slow, and only slows down until it stops, and within a few minutes, I get a message saying the server has reset the connection
Hmmm... I just tested the last link I posted, it downloaded quickly and just fine for me, so I know the file is there and the link works. I'm wondering if it has something to do with your location - I myself and the hosting company I use for my site are both in the United States - What nation are you from?
I also know that in the past my hosting company has had service outages from time to time, although such outages don't usually last more than several hours, it might be something you could just try again at some point - Over the last few days there has been nasty winter weather here in the U.S. that has resulted in over 1 mil. people without power at one point, I don't know if that made any difference.
Also, quite a few people download these development builds, it is possible many people were trying to grab the same file at once.
I don't know what to suggest other than to try again at a different time, or ask Muton to post a link for a full install package.
I'll also check settings on the control panel for my website later, and see if anything jumps out at me as being wrong.
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And for the other issue:
If I remember correctly I tried using this one: http://ufoai.streetofeyes.com/Codeblocks.zip
Honestly I still don't remember how I fixed this issue (I had the very same problem before myself) when it happened for me. If I recall later what I did, I'll post another reply, otherwise you can post a separate thread asking for help with compiling, and one of the coders can help you. Sorry I don't have more information at the moment... (I'm actually not one of the project coders here.)