It offers some barrel rigidity (that's not necessary for airsoft), but to manufacture a fluted barrel, it does cost more than a straight one, and hence, the added cost.
If you want something closer to realism, get the fluted, otherwise, you're fine with a straight barrel.
As for your question regarding CA and TM, that question's been asked and answered about a million times. Check the airsoft guns discussion forums for the x-billion number of different responses on the issue.
Last edited by ILLusion; August 5th, 2007 at 15:37..