Here in Michigan, your blood alcohol concentration would have to be 0.08% or above - in order to be charged with a DUI.
.08 bac
yes.. a minor can get a DUI at .02 bac if your underage you can get a DUI at any bac.
DUI isn't a felony offense until the third or fourth depending on the state you live in. You can be charged with felony DUI in some states if your BAC is above their legal threshold.
If you have been charged with a felony it is possible that the prosecutor could have you charged with a misdemeanor DUI if they decide your case merits it. Some felony charges are required by law if you have multiple DUIs or had a BAC that was very high.
BAC legal driving limits are the same for minors (under 21) as for adults. The only difference is that if you are under 21, in addition to being charged with a DUI or DWI you will also be charged for underage drinking. My suggestion to you is don't drink until you are 21, and always have a sober driver. In Oregon you will be charged for DUI under 21 if you have ANY measurable amount of alcohol in your blood.
.025 BAC
Yes, it is, especially for a minor, for which a zero tolerance limit is imposed.
Yes, 0.08 BAC is the legal limit in every state.
.08 is considered the legal limit for intoxication, so a DUI charge will not be applied. However, if you are over 21, any BAC over .02 can lead to a DUI charge.
While most states have a presumptive BAC limit of .08, you can be arrested and convicted of DUI/DWI/DUII or driving while impaired regardless of your BAC level. In general all that is required is that the officer believe that your driving is impaired.
.04
That will depend on the specific laws in the jurisdiction. In general, anything over .08 BAC is considered a DUI. There is no 'upper limit.'