Getting better

Hi and welcome to Buf. I think you'll have a greater chance at getting answers here UT2004 forum

Hi, and welcome to Beyond Unreal Forums.

As for your questions:
1) See Hal's post
2) wow, there's an official guide to UT2004? I haven't read it, but I'd have to agree with Hal. For example: the link in my signature, which points to my guide, contains about every advanced tip I've come across on the internet. And it's completely free to read
3) instead of "just" practicing the game, try an approach that trains specific skills, one at a time. Play duels until you can effectively predict the enemy's moves and time the 100 shields. Use Angelmapper's target practice mutator if you want to improve your aim. Try 'skills' assault maps to improve your movements (I recommend AS-TempleOfTrials-v4). Play against a Godlike bot (or even a team of them), but instead of fighting him/them, try to outrun him for as long as possible. Play a lot of instaGib. Use an arena mutator to train certain weapons. But whatever you choose, make sure you don't set things too easy. The only way to improve is by doing things that are a bit harder than you're used to. If your win doesn't feel like an accomplishment, make things harder for yourself.

Hope this helps

PS: nice signature. I might use it in a guide someday.

http://www.communityreload.com
that will help alot