Considering purchasing 5E SRD
 

I already have HL for Pathfinder, but thinking about getting the package for 5E. If I want the extra rules from the Sword Coast book, is there an add-on for that and how much is it (I can't seem to find a link for available 5E add-ons)? Is the Community Pack free and is it useful for DDAL play?

Yes, the community pack is free, and it is great, the people that have worked on it are all volunteers, and have done an absolutely Awesome job.
When and after you buy it, follow this link, it will explain all you need..

http://forums.wolflair.com/showthread.php?t=55090

Is there a separate add-on for Sword Coast rulebook? How much is it?

Also, from what I can tell, the Community Pack has very limited implementation of Sword Coast rules. For instance, I'm initially interested in all the Paladin additional Orders and Oaths. None of that appears to be in there...true?

All of the community stuff is free. LW doesn't have any official WotC add-ons to purchase. Kobold Press has the most purchasable stuff available.

The community pack has the Oath of the Crown included in the SCAG stuff. When you download the community pack, you gain an expanded character options menu where you need to check the checkbox next to the community packs you want to enable on a character. You see these options when creating a new character or when you hit Ctrl-K on an existing character.

I think daplunk hasn't updated the post you've used for research, the newest notes for the community pack are often found here.

I don't think the community can support the orders of knighthood beyond providing the name as an existing "membership" choice, most of the "flair" can't be replicated without LW getting a full WotC blessing. There is a spot on the Background tab where you can add a custom membership though.

Great info, dungeonguru...thanks!