Plus net Pro

[#1]

Does this option mean that usenet would not be capped and we wouldnt experience sppeds of less than 100kbs?

[#2]

yes everything will run at line speed on pro. http://www.plus.net/support/broadband/quality_broadband/speed.shtml

[#3]

Unless you are trying to download Avira updates 
Edit - to clarify - this is an Avira server problem not a Plusnet limit