At Lvl 7 you can take whichever talent, though since this build focuses on Long Range, I'd suggest one of the traps, Big As, is good for some nice burst damage for you and your team, whereas Sticky Wicket is really nasty due to a 2 second silence, while being rooted, especially this talent paired with Lvl 13 Gotta Trap 'Em All! Makes it a literal minefield for the enemies to wander through, and a hero or 2 being silenced in a fight is insane value.

At Lvl 10 take whichever ultimate you prefer, though if you're long range I'd suggest RIP-Tire, it does a lot of damage and gets somewhat easy to control after a cast or 2, and the explosion radius is fairly big.
Rocket Ride is good if you want to have a quick escape more so than taking it for the damage, though if you have a root or stun on your team that makes it easy to hit, it's also a great ultimate that the impact alone can take away half most enemies healthbar.

At Lvl 16 it's simply your prefered choice, I like Endless Nades as, by the name, you can use Frag Launcher over and over again and do a lot of heavy poke/burst damage.
Spread Volley is a great active talent with a 30 second cooldown, which is its biggest problem, but against a very spread out team it'll do a lot of damage, it's very valuable against a healer such as Lt. Morales, who can only heal 1 target at a time(2 for a few seconds if she's talented into her shield).

At Lvl 7 you can take whichever you prefer, it all depends your playstyle and the enemy team setup. Sticky Wicket if they depend on being able to cast, Big As if your team can burst picks, Bogged Down is more if your team can pick up slow enemies, and Dirty Trickster if you're in danger.

At Lvl 10 you can pick whatever you prefer, but I'd suggest Rocket Ride for being able to get out of any situation as long as you don't get cc'd and can come back within 5 seconds due to the mount effect it has, with full health.