As for faster, maybe? It depends on the metrics and what you're doing with it. If you mean TPS, no, I get much higher TPS and even faster TTFT on my local setup than frontier models. If you mean time to complete tasks... maybe. If you're throwing whole projects at it to vibecode, yeah, a frontier model will dump slop so fast it'll make your head spin. If you're doing actual methodical development, like doing spec-driven development and actually reading the specs before spinning off agents to implement them, rather than just having another agent review it and yolo, you'll find that frontier models don't really push the needle that much, and you'll be making high-quality projects.
Yes? If you're building anything reasonably complex, it is a ton of work to keep everything in your head so that different parts of the system work seamlessly and work you do in one area does not adversely affect another area.
Also, yes, I do need the capabilities beyond what can be reasonably achieved with local models because threat actors are also using frontier models.
This really depends on your infrastructure. In this case it all depends on your hardware, and there is no secret sauce, you can buy the same GPUs or better than the big players are using. Self-hostef GLM in our company is faster than any commercial model. Of course the hardware was not cheap, but completely manageable for a medium or large company.