Echo integration would be handled separately, typically by setting up a virtual switch that turns on the scene you want. Then you can tell echo to turn on that switch. Very similar to what people do with a button controller like a minimote.
As far as smart apps to handle scenes, there are a couple of possibilities. Each one has somewhat different features just depending on what the author was interested in, so you’ll need to look at them one by one to see what best would work for you.
"Hue (re) connect " is probably the most popular, but “simple scene manager” is simpler and some people prefer that. There are a couple of others that might work as well, although I think with the others you have to build your own scenes from scratch in the smart app, they don’t integrate tightly with Hue.
The easiest way to find these is probably to look under lighting smartapps in the quick browse lists in the community created wiki.
Another possibility is core. This is a very sophisticated community created rules engine. Very powerful although setting up individual rules can be quite complex. There is a peer assistance thread to help with that part. I don’t think it can import hue scenes, but you could set up your own.
The main advantage of core is that it allows stacked conditionals so that you can say “If A or B unless C while D is happening” and that sort of thing. So a lot of setup work, but a great deal of power. ( A “piston” is what core calls an individual rule.)