Hey everyone,
as the title says, I'm planning to start with Eldar and don't have a lot of experience with
40k (or tabletops in general), so there would be a few (possibly rather noobish) questions I'd have. If the questions indeed are too stupid and and none of you want to bother, then that's really alright ^^'
I also hope this is the right forum to post this in
On a side note, I've read the rulebook and codex cover to cover a few times and I *think* I at least have some basic insight on how the army works, so it'd be good if answers weren't too general (i.e. "Firedragons are your anti vehicle troops", I know as much

)
1) Dire Avengers and Guardian Defenders
I know both seem to have their place in the army, but especially here on dakkadakka (and especially by Stelek) Guardians seem to be preferred over Avengers. Um... why? Is it because of the higher cost of
DAs, the lack of versatility (weapon platforms)? What do you prefer to field, personally, and why? For me, they seem to be more or less the same bar the obvious, so honestly I don't really know what to get.
The reason this is a problem for me is because I might get the Eldar battleforce (5
DA incl Exarch, 10 Guardians w/ weapons plat, Waveserpent, Warwalker) and I'm not sure if I should get another box of Avengers (5 seems way too small at any rate) or drop the Avengers and go for 2 Guardian squads
2) Warwalkers and Vypers
Here, again, I would see viability in both units. Warwalkers can dish out an impressive amount of shots, but from reading a few threads here I understand it's difficult to get a coversave for them, plus they are rather slow, especially compared to Vypers. Vypers on the other hand zip around the battlefield, but are less shooty and more vulnerable (open topped?). Since I'm going to start small (500 points first and increasing at 250-ish points steps) I don't want to mix those units really.
For a less mobile army Warwalkers seem to be good as a firing base, while Vypers could be a fast response unit. In a mobile army (the Windrider Host box looks interesting, 9 jetbikes, Autarch on jetbike and 2 Vypers), Warwalkers seem awfully slow, but again, could possibly put some hurt on units from afar in an army that lacks range and anit-vehicle (again, at 500 or so points, this time in a jetbike army), and Vypers being good to stay with the rest of the army.
Keep in mind, all this is my opinion as a beginner, lacking the insight of long-time experience, which is why I'm looking for some input.
3) Are there any units I would be better off trying to avoid? For instance, Shining Spears don't seem to get used often, neither do Warpspiders or Swooping Hawks (only in small qualities). What would a "competetive" list at 500 points look like? (using standard force organization charts it might not be competetive at all Xp)
I think that's it for now, thanks in advance for any advice