I completely agree with your first point. Being able to actually delete boards would be great, rather than having 5 archived boards.
I disagree with your second, but am genuinely interested as to why you might want this.
The idea is with Trello and other kanban systems is you move tasks from the left to the right. If your intent was to create another type of transition, you're breaking the underlying concept. If your intent is to break up a single list into multiple small lists for organisation, could you use something like colour coding instead?
edit: have just read further down that they don't intend for it to be a strict Kanban system, so perhaps there's room for multiple lists in a column. I'm still interested in your specific problem though!
Imagine the value Trello brings you today. Imagine the value it brings you with these two features.
Is it really different enough that it crosses the threshold of being worth using?
I find that hard to imagine. How much time do you spend looking at archived boards? What would you do with two lists in a column that you can't do today with one list that has some "subtitle" cards?
I'm asking because I'm genuinely curious to know use cases like that, not rhetorically.
My own problem with Trello (that I use a lot despite that problem) is that I feel the need for more than one view of my data, i.e. sorting it in more than one dimension. Perhaps having the ability to have two boards with the same cards. Unfortunately, I cannot imagine any good UI for this.
I wish cards could be tagged. I use labels for overall categorization but I need tagging to tie cards back to our project management system (which I find unusable for actual project management). Currently I just make the first line of the notes my faux tag.
It's s minor gripe though, Trello is pretty great.
Trello has quite a good API that you can use. It's trivial to hook it into whatever other system you happen to use. We linked Trello to our Redmine ticketing system, and it works pretty well for our needs.