1. "place" is OK; "pose" is wrong.
A couple of other corrections:
"It is very important to be aware of the CCS dilatator length since using this technique we wanted to place the tip of the guide wire in level with the tip of the CCS dilatator."
2. I don't see any underlining.
3. Bearing in mind that I have no knowledge of what you're talking about, yes, I think so.
More picky comments: There is a slight mismatch between "It is very important" (abstract) and "since we wanted" (personal), so you might want to consistently use one style or the other. "using this technique" is slightly awkward where it is. You might want to shift it to the beginning. So, you might end up with something like:
"When using this technique, it is very important to be aware of the CCS dilatator length since the tip of the guide wire must be placed level with the tip of the CCS dilatator."