I had a 2008 135 and awaiting arrival of my 135is, so done this twice now.
If you don't buy the alarm, it comes with no alarm. A lot of people get it, somehow it seems to me alarms do nothing, especially in big cities. You could always put one in cheaper afterwards, too.
On the premium package, just up to you and if the additional options in the package are worth that extra $1,000 for you since seemingly comfort access (normally a $500 option) is available for free somehow. I will have confirmation of that in a couple of weeks when I get mine, in which case you may want to save the $1,000 and not get the premium package and just get the leather as a stand alone, and before they seemingly close that comfort access loophole.
Also, if you want to see what it looks like on a space gray 135is with the rear parking sensors to see how noticeable/annoying the sensors look to you, check out this one online. Granted, the pictures are all skewed and weird and the lighting stinks, but it's space gray and has the sensors:
http://www.bmwofbeverlyhills.com/new...0ce7caa42e.htm