Not original commenter but same shoe: the answer is yes and yes. Small companies has their perks and drawbacks :) And my view on seniority is definitely skewed: I would say I expect a senior engineer to handle a large(multiple month) task, rip it to pieces, make a rift out of it and handling out paddles for the other team members while talking through the hard shit with other similar minded persons in the company. I'd also expect correct ballpark estimates.

What I do not expect is the business part - decisions, communication with the client, money stuff. I also don't expect responsibility for all of this on one person - this is where multiple roles comes to play as one person could break it's spline from all this.