25mm for Flow and Arch rims, narrower tape for the rest of the ZTR range. I bought mine a couple of weeks ago and have put the yellow tape on with the Olympic valves. I've put UST Nobby Nics on and they pumped straight up with a floor pump, no faff whatsoever. Put a bit of sealant in and job done. I've not tried a standard tyre with just the rim tape, but I reckon they'll seal ok with just the rim tape.
Rim strips are only needed on non-tubeless rims. ZTR rims hold the tyre in place so well the yellow tape is all that's needed to make a seal. Plus, if you use rim strips, you might have to enlarge the valve hole on ZTR rims and you can't go back to using just tape once that happens!
My recommendation is to go the whole hog and set up your system with decent UST tyres. If you've opted for ZTR rims in the first place, make the most of the advantages they give you. Running my front tyre at 25psi!