If you're referring to the Vocaloid 5 feature of attack and release's pitch section, you have to manually make the pitch edit with the control points on the notes. You can add control points to notes by selecting them and right-click then pitch. In the Pitch control window, you make sure portamento is checked and click on the add control points, selecting how many you want in the drop-down next to "add ctrl pt". After that, you just move the points around till it is what you want it to sound like.
If you want something that's essentially pre-made pitch edits applied to the .ust file then there's a plugin called AutoPitchwriter, which can be found here.
Besides that, there are flags that can mimic some things such as breathiness. Here's a list of flags and what they do. To apply them you select the notes and right-click on them, then property. There, there is a box named Flags where you type in the flag and its value. If you do not see the box click on the "Details" text in blue.
'Attack' means how quickly a note reaches its full volume. For instance, the background synth in the intro of Circus-P's 1/4 will have a high attack, since it doesn't reach it's full volume immediately as the note is played.
In UTAU, that could mean one of two things, since 'attack' isn't a feature. This could mean adjusting the oto's as you've mentioned, by cutting out the silence at the beginning of the recording and making sure not too much vowel makes it into the 'consonant' part of the oto.
Otherwise, if that's all fine and dandy, look at the consonant velocity. This allows you to adjust the speed of the part of the recording you've highlighted as the consonant. This is probably what they're referring to. The default setting for this is 100. Guren no Yumiya is quite a fast song, so I'd try adjusting it in increments of 25 until the lyrics sound clear.