Yes, in Logic you can automate aux send levels to your delay channel to only come in for those words you select.
There are several different types of delay FX available in Logic 9 and there is a huge variety of settings available for each type.
You could also try copying the words you want delayed to a separate audio track and apply the effect only to those, but it would mean also duplicating all other plugins so that the tracks have identical pre-effect 'processing' and sound the same.
Logic is definitely in the 'pro' range of audio & midi composition software, of which Protools is also a huge player as it is found in nearly every professional recording studio across the globe. Either software package will give you plenty of scope for achieving the effect you have described, however only protools10 will allow you to work with non-Digidesign/Avid AD/DA hardware. Previous versions will require you to have a Digidesiogn/Avid hardware interface.
Logic will work with anything *including* Digidesign/Avid interfaces.
Logic DOES NOT support VST plugins, and hasn't since version 8, which sucks copious amounts of butt as I have purchased VST effects and instruments for previous versions of Logic and can no longer use them (thanks very much Apple, you bastards).
Having said that, all IK Multimedia AU format plugins (and any other AU format plugin) will work in Logic.
Logic 9 also WILL NOT run on a Windoze ( ) machine, so have a serious think about whether you're able to afford to make the jump to working on a Mac if you're currently in Windoze land.
I don't suffer from insanity; I enjoy every minute of it.