Rifle/SR is fun, I've done some serious overachieving with lamp/baum backed by melee/CMG. Missiles definitely help. Ive always come back to fragrant with this weapon set.
Missiles help alot, especially on this build, especially since you can use it to help dish out extra damage and some stun sometimes. This actually the one type I wish the Habas didn't lock so fast with Otkryt. That was my complaint with it back in ACV (couldn't throw them out fast enough), and now it's reversed.
I don't remember the SR stats but will it cause stagger? On high firing stability arms it could act like lampeye back in ACV but i don't think SRs hit that hard.
Nope, and even if it did, it doesn't do it reliably because of how stun is in VD. It's a shame really, because it would have given a very strong reason to use the Seidenbaum with its naturally higher impact force, but that isn't the case. Most of my tunes are focused on either balanced or reload/accuracy oriented to make up for lock time.
I find that mid heavies to heavy bipedal builds aren't very effective unless they're in a team. I personally don't find them very threatening. Heavy reverse joints are a bigger threat than a heavy biped.
It's more of a personal preference than anything. The Tolima type legs are meant to be a fusion of the mid and heavy legs; unfortunately, it's not perfect, and it lacks many advantages of either legs so it suffers alot in comparison with other builds. Nowadays it seems most fast heavies are limited to either niche sniper or kicking roles although I do love to experiment with them alot.