Seems to me it’s not Beeminder that’s anti-habit-forming, it’s increasing your safety buffers that’s anti-habit-forming.
Isn’t that the whole point of increasing your safety buffers? If you want larger safety buffers for a certain task, doesn’t that mean you don’t want that task to be a daily habit?
Conversely, suppose you want a task to be a daily habit. Seems to me the rate for the associated beeminder goal should be 7/week (like you suggested in your point 1) and also set it so you can only record a max of 1 per day - in other words, make it impossible to have a safety buffer.
If your goal rate is less than the actual rate that you want to do the task, Beeminder will encourage you to do other things once you’re past the goal rate.
Some people have found encouragement in changing the colors so all the goals turn green - you could also try to motivate yourself to accumulate more and more buffer (if you’re allowing your goals to have buffer, that is)
Check out: Colors More Motivating Than Money? and Feature Request: Color-ratchet
Why do you want things to be habits? The way you’ve set it up, you’re now doing more urgent tasks instead of habitual ones, which seems better to me.
Also, there’s some debate on whether habits even exist as such: Do habits exist?