This is a no-brainer. Yes. Get him the best DUI lawyer you can find in the area. He is looking at a posible felony due to the injury. Even if this is a 1st offense, he could spend considerable time in jail.
I don't handle lawsuits against government agencies, so I can't really comment on your chances wining something like that. I handle DUI cases. What you could do to help others in the future is make a written complaint against the arresting cop. All you really need to establish is that your blood was completely clean from anything an that he still believed you failed the FSTs, and says he saw signs of impairment. This would be used by defense attorneys in the future to show that these tests are...
The page that really needs to be signed is page 1 of that form. The pink paper you got is page 3 (read the top). So you don't know if page 1 is signed or not. It wasn't signed at the time they handed you page 3, but it may be signed by the time the officer gets ready to send it to DMV. So, it likely means nothing. Business as usual.
Speeding in a construction zone could have an impact. Speeding more than 20mph over the speed limit might mean the prosecution will ask for 60 days jail even on a...
Hire a DUI attorney immediately. Sometimes there are flaws in the pink temporary license they gave you allowing you to still get a hearing past 10 days. You may also be able to get a hearing if the charges are reduced in court. You don't need a hearing if you are found not guilty in court.
I agree with getting 2 lawyers because I don't think any lawyer would be an expert in DUI as well as administrative law. The DMV process is administrative so a DUI attorney will know about that specific administrative process, but not the BBS.
I agree with Mr. Murillo. However, I would add that there may be a strong chance you can have the DUI dismissed if you hire an experienced DUI attorney to file a motion sometimes called a Serna motion (other times referred to as a Doggett motion).