It is not uncommon for the district attorney to request additional information prior to filing a case. If that information is not received before the arraignment date then a case may not be filed until later. As stated above, the district attorney has one year to file a misdemeanor case but generally they don't take that amount of time for a simple DUI/resisting case. As previously mentioned - check with the court regularly, you are better knowing when/if charges are filed than finding out...
Should the DA choose to take this case to trial, it is likely that you will be asked to testify because you are the victim in the case and you have the details of the incident. As previously mentioned, if the DA chooses to make an offer and your boyfriend pleads then you will not testify. Additionally, the court may give an indicated sentence that is acceptable to your boyfriend and he may enter a plea as charged without risking a trial.
The filing officer does not press/file charges the District Attornney does. The filing/report officer merely takes the information and forwards it to the District Attorney's Office for review and filing.
The information provided does not indicate if all charges are filed a misdemeanors or if the PC459 and PC530.5 are filed a felonies. Whether you plead to a misdemeanor versus a felony will greatly affect your sentence. However, there are also potential alternative sentencing strategies that you may be eligible for in lieu of actual jail time.
In addition to what the other attorney mentioned, it tends to indicate to the court that you may have a problem with alcohol increasing the possibility of some type of program to address your drinking and choices while drinking.
Any time he is looking at depends on his prior convictions. You indicate he has two prior prison allegations (+1 year each) but don't mention what those offenses we're. If they were strike offenses the time he is facing could be increased. The 459 - 2nd degree carries a term of 16 months, 2 years or 3 years in state prison and the 667.5(b) allegations are 1 additional year each.
It is my understanding that the DMV requires the completion of the program not simply the passage of time for the suspension. Regularly the courts will indicate that a defendant must comply with the DMV requirements as a part of the probationary period. Failing to comply with the program may prevent you from obtaining a license.