Confused- Plusnets definitions of what's what

[#1]

Sorry for the stupid questions, but I'm struggling to decide whether to upgrade and to what.
The one thing I really don't want is to be any slower, but I can't figure out what will actually make me slower.
What does constitute a download site/server?
Is it just the list on this page https://portal.plus.net/support/broadband/speed_guide/download_servers.shtml
Or does it mean..... well everything. Ebay, Wiki, forums etc. 
I had a look at what we've been using and it says we are 73% web, 24% streaming, and 3% other, so I just have no idea. 
Thanks in advance for any help. 

[#2]

most of the throttled sites are listed at the lower end of your link, the oddball one is Akamai, there are some well known companies there, some PN give a signature to the so that they are not throttled.  but some like Microsoft and Apple are

[#3]

What account are you on currently and which account are you considering?