There are 2 choices, AdvExt and Vanganth. I believe both are the same, if there is difference, it's almost not noticeable. So, it's up to you. Vang is not supporting ppl w/o knowledge, so your only choice is AdvExt.
But git may block your repo, as they did with all java projects before. There is Bitbucket also. Anyway, doesn't matter what you choose, old school svn is fine, so go with xp-dev :)
Nothing in my mind. I have the same problem with my net provider. They say that they block nothing, I make rules, disable windows firewall and still nothing. Dat windows OS.. Try Linux :D
You have to understand one thing. There is no perfect pack. Take any pack you want, faced issue? Report it to owner (sunrise case) > they fix it. Otherwise, pay someone to fix it. You will pay less than buying "pro" packs for xxx euros.
Sure, you can go for l2scripts. If you want to waste hundreds with no sources.