I'll try to help you.
1. Under "installation" you are only selecting the Sonar, not the LSS2 ( meaning the LSS2 is good to go once you screw in the cable on the rear of the HDS unit ). There should be a tag close to the blue sonar cable/connector that goes in the unit. On that tag is the transducer type/name and that is what you select under installation. You can select generic, but it's best to select the correct TD type.
2. Click pages button ( top right ) and select the Structure icon. In order to get Down Scan, there's a bar on the right hand side of the screen with some options. One of these says "view". If you touch it, it will open a new view and show you several options: right side only, left side only, right + left, and down scan. NOTE : You can have a spilt screens and one can be left+right and the other can be Downscan all on the same page.
I would recommend doing a search on YouTube on HDS TOUCH and you'll find several "how to videos". Some Are [censored] but generally they are very helpful.
I know the manual might be tough to understand, but I HIGHLY recommend you read it while your sitting in your boat ( in the garage ) and play with it.
Hope this helps.