What type of clearance you need for the 15T MOS?

Secret level. I had way more, it got me doing fun stuff no one else in my entire Batallion including the Intel officer could do. Don't worry about it, put in for the school. When you get accepted, they will do before you graduate.

Secret, for the avionics and counter measure systems I believe

You will have a Secret clearance before you leave AIT or you will be a holdover. and unless they've changed everything, a 15T is a Blackhawk mechanic. 15Y is an Apache mechanic

You don't need a clearance but the SECRET clearance is the clearance you can get and it's good for only so many years , they usually won't worry about clearance until you deploy. We've had to recertify our clearance on each of our deployments.

Well actually.... there is always the DAP 60M.

Depends on what unit you will be with. Like at one point the 160th may come through the company, and see if anyone is interested and if you do that you will more than likely need some kind or clearance but other than that no.

you only need secret. Any arrests for the last 7 years and any alcohol related incident, EVER. They will find it.

I don't think they issue Confidential clearances - I have never seen one.

There doesn't appear to be a clearance requirement for this MOS in the quick Google search I did. If you needed a clearance for something else, most likely all you'd apply for is a Secret. A secret you usually go back 7 years on the SF86 (you can find it online to see what you have to fill out). A TS you'd go back 10 years initially. But I don't see that you'd need a TS. Also definitely not a polygraph. I have only had to take one polygraph as military intelligence and that was when I went to Cyber Command when it stood up and we worked out of the NSA buildings. It was not a lifestyle one either.

This is on the go army page for 15T: http://www.goarmy.com/careers-and-jobs/browse-career-and-job-categories/transportation-and-aviation/uh-60-helicopter-repairer.html