Yes to both.
I have been changing settings while the darksend process is active, I for example set the amount to anonymize to 2000 tDRK the process started normally, then moved the setting down to just 1tDRK, before I had any actual anon coins, the process just stopped and stayed idle for hours until I raised the amount again and then it started again. To me that was the expected behaviour although the soft limit is a little bit confusing. Also suspending the computer at different times, didnt produce collateral charges I guess that is good?
What I am really wondering now is how it will work with small wallets, lets say you have 45 DRK and want to mix 5DRK, maybe below a certain threshold you should be forced to anonymize your full balance. Anyway, if DRK price keeps rising smaller wallets will be more common so I will concentrate my testing efforts there.