I havnt fully understood the manual but obviously the humans will have guns which can shoot distances but what about the aliens? do they have to be close range to attack do they have a umm long range sort of attack?

This differs.
All aliens have melee attacks, but most (kept for the Skulk) also use ranged weapons, such as Spikes, Acid Rockets, or the half - distance attack of the Onos, Paralyze.

The skulk actually has 1 ranged attack, and 1 semi-ranged attack. The skulk's :parasite: attack is a ranged projectile that is shot out and used to tag marines. (they will show up on the hive mind, if they are parasited)  It also does a around 5 damage. (horribly embarassing if you die by it).

It also has xenocide, which is a self-explosion attack that has a radial damage effect.

Xenoside is basically a suicide attack.. but damn cool.
as it says in the manual. A well placed xenocide attack can take out an entire squad of marines.

Also there's the Gorge's spit, bacterial spray (semi-ranged), and babbler (it's like a snark from HLSP), the Lerk's sporecloud (ranged eplosive-like weapon), the Fade's bilebomb (ballistic, mortar-like explosive) and blink (ranged teleport).

lol just listening to the attacks gets me impatient for the release    

dude... can u wait 20 hours 31 min?

Quote (Cyanide @ Oct. 30 2002,11:55)

[...]The skulk actually has 1 ranged attack, and 1 semi-ranged attack. The skulk's :parasite: attack is a ranged projectile[...]

Tell you what - the first time you kill someone with Parasite, and Parasite alone, I'll correct my statement

Hey about the skulk and its Xenocide.
Does it impair movement so u cant chase marines?  Well probably.  But what if you were on ceiling and activated it, could you drop down and blow em up, cause I am assuming its not an instant detonation.
Activate, drop, BOOM!, Nice to know you.

The only caveat to xenocide is that it takes a second or two to go off.  You can still move just fine.

Quote (Evil Sonic Death Monkey @ Oct. 30 2002,21:29)

dude... can u wait 20 hours 31 min?

I'm an impatient person :/ also will the aliens generally have mroe speed over the humans, cuase i'd love to see a human run out of ammo then run from an alien catching up to him and then pounce on him

Forgive a heretic, but will/are the battles basically like Starcraft in FPS form? I keep getting images of Hydralisks and Zerglings tearing into marines. Is this the right mental picture or do I need a paradigm shift?

I don't know if im right but when I think of battles ambushes come into my mind and hit and runs well for the aliens at least.

I dont generally have a idea of how its like all i know its gonna have aliens and humans running arond       vs

Skulks and (flying)Lerks are faster than marines, Fades, Gorges and Onos move abour the same speed as marines.  Of course Fades can "blink" and Onos can charge to get a speed boost.  All the aliens get faster if they have the Celerity upgrade.