The product I use (Appigo Todo Cloud) can do some of that but not all. I have created lists for Next, Waiting-for & Someday. I mostly put single action tasks on these lists but sometimes also smaller multi-step tasks (i.e. created as 'project' or 'checklist' tasks.
For larger, longer-term multi-step projects, I create a separate list for each one. This puts them in the left-hand menu below my Next, Waiting-for & Someday lists where they are always visible, i.e. my place-markers.
Todo has lots of neat features but it doesn't do any auto-sequencing/activation. That's a not a problem for me because I tend to not fill up projects with lots of pre-defined future actions. I just put in one or sometimes two steps at a time because things may change in the interim. Being always visible helps me think about what I need to do to progress them.
I saw your post about start dates over in Appigo but haven't had the time to absorb what you were asking & respond. But in case it helps, there is a general setting "Hide Tasks starting after" which can be set to none, today, tomorrow, next 3 days, one week, two weeks, etc. I use start dates occasionally to force a task that's due in the future onto my list earlier so that it prompts me to start working on it. I don't use the start field to hide tasks.
Todo has a tags feature that you might be able to bend for use as your universal container. I just have two tags and use them as a switch for my area of focus, i.e. 'business' and 'personal'. Although I've noticed that I rarely use the tag filter anyway so it's probably just another point of friction that I don't need to use.
I'm doubtful Todo will cut it for you if you're used to some of the deeper Nirvana features, but Todo's simplicity is what I really like about it. It looks clean and is easy to use but is quite powerful underneath. The web interface is better than Toodledo but probably not quite as neat looking as Nirvana.
However the mobile apps are where Todo really shine - this is where Appigo started and the latest iOS7 versions on the iPhone and iPad are beautiful and a joy to use. In my view they are one of the best iOS developers - they really 'get' good UI design. So I rarely use the web version of Todo anymore - I'd rather pick up my iPhone or iPad to work on my lists.