It's relieving to know that I'm not the only one having problems downloading. Having never used Technic before, I wasn't sure if I was doing something incorrectly, or if Tropicraft was somehow not downloading properly (as I've been trying to download that specific mod, multiple times, for at least two hours). Decided to take a look at the forums, and found this one. Currently at 80% with my fingers crossed.
Thanks to everyone who is working to fix the problems, and best of luck to the people dealing with them. :)