What exactly are you trying to accomplish?
Unless you are willing to go all the way to trial in the unlikely event you are somehow successful in being permitted to withdraw your plea with this much time passing after sentencing, you are wasting your time and money.
You can still be charged under Vehicle Code section 23152(a) (Driving Under the Influence of Alcohol &/or Drugs), and in some instances Vehicle Code section 23152(b) (Driving while having .08 or higher BAC).
The .05 helps your case, particularly if no drugs were involved, but in the event you wish to be reactive instead of proactive and wait and see what, if anything, is filed THEN hire a criminal defense attorney, so be it. However, it is always advisable to be proactive.
Obtaining a dismissal under Penal Code section 1203.4 (commonly, and wrongfully, referred to as California's "expungement" statute) should not have much, if any, an effect on the immigration status issue. Contact an experience immigration attorney for the best advice moving forward.
Hire the best criminal defense and/or civil defense attorneys you can afford. They might be able to give you a reasonable estimate as to what, if anything, your insurance (assuming you had insurance at the time of the collisions) will not cover.
It appears that "the charges were dropped" to a misdemeanor (maybe), but you are still on probation. Thus, by allegedly violating for failure to remain law abiding, you may be facing a new charge for the possession of marijuana along with a probation violation for the older case.
You certainly need an attorney. Hire the best locally experienced criminal defense attorney you can afford.