I noticed that there are no trees and not too much environmental objects. I know that SpeedTree is coming out for UE4 and then there will be Trees. There is also not a Sand Material or object. I want to make a Tropical Island and have Grass in the Middle and a beach surrounding the island but there’s no sand material. Is there a Sand Material coming soon? and when is SpeedTree coming out? I was also wondering how do you place water going for miles, I see game engines just like drag water into there game and it goes for miles. Thanks for your Help! 
SpeedTree is coming out with 4.3.
You can find sand textures anywhere on the web and make your own textures quite easily. You can start with http://www.cgtextures.com/
For water all you need is a plane mesh. The material is up to you, or you can find some premade materials and fantastic looking & behaving ocean plug-ins in the forum.
Hi!
For the first release of the Starter Content pack we did indeed keep the scope down to mainly architectural elements. It is funny you mention this because in our initial review for the starter content we had many more wood/bark/nature textures but we decided to narrow down the scope for the first release since there was a lot of polish work to do and we decided it would be better to ship a few high quality assets now and add to them later somehow, rather than try to cram everything in to the first release and possibly compromise the quality (ie, it takes a few hours to fine tune the ‘tiling’ of each material once you get it looking good).
I believe the new speed tree should be releasing alongside UE 4.3 which should be soon now.
4.3 will also have a landscape demo that has a few more nature textures. I believe there is a dirt texture but I am not sure how well suited it would be for sand. Sand could be lots of things. Are you thinking more like S shaped wavy sand or just simple beach sand with random lumpiness?
As far as water, you can easily make a big water plane simply by adding a static mesh plane (there are some in the engine folder) and scaling it up by a massive amount. If you author your materials to use worldposition rather than UV’s there will be no stretching.
Visit here for sand materials
Sand materials