Phone-as-modem is not included with that plan, but if you have the PPC-6700, Samsung A900, A920 or A940, you can disable NAI and tether for "free". The regular phone-as-modem rate is 0.02 per MByte I think which is not that bad in a pinch.
Text messages are unlimited.
Also, if you are good friends with a Sprint employee you can get an even more insanely cheap plan, but they would have to take responsibility if you don't pay your bills, so make sure you're really good buddies .
Text messaging is not part of SERO. If you got it, it's something you got separately.