New gun and upgrades

First, read this, it will answer oh so many of your questions; www.airsoftohio.com/phpBB/newbie.php

it's DumboRAT's Newbie FAQ.

as for bbs, here is Wallace's ultimate bb test

www.airsoftohio.com/phpBB/viewtopic.php?topic=928&forum=18&19

for springs; www.ucalgary.ca/~airsoft/UCAC_New/articles/aegSpringChart.html

this give you pdi and systema spring conversions and theoreical FPS. The figures are a general guide to fps, they are not the exact numbers you will get. I have a pdi 150% that shoots about 370 (or so airsofttoys told me), and Newman has a 150% that chronoed at around 345.

I've never heard of airsoftwarzone with the exception of one thread earlier on these forums where Hado stated that he had never heard of them.

this is the seller rating seller rating section at airsoftplayers.

www.airsoftplayers.com/sellers.asp

look through the different retailers for information on them. just remember that for all retailers, ask for a full quote, and for retailers overseas, you will have to pay usually over 50 bucks for shipping, but again, ask for a full quote to know exactly. Also know that when ordering from overseas retailers, especially now, you run the risk of custos seizing it and you either not getting it, or getting it after waiting for a very long time.
I personally reccomend www.airsofttoys.com, www.wolverinetactical.com, and www.mdairsoft.com . the first one has the bigger selection listed on the site, but the other two can get anything that airsofttoys can. they all use the same distributor, WGC. wolverine tactical is right in michigan. if you're anywhere near grand haven, you can go in and pick it up to avoid paying shipping and waiting. but it only takes them a day to ship to pretty much anywhere in Michigan. They have the best customer service i have ever seen. the owner, Mike Sabatino a.k.a. WTS-Mike is a member here on these forums. He's a great guy (although a little heavy on the sales promotions , but we can't blame him for trying to make a little money)