The fact that there are current proceeding against you will affect any application that you submit at this point, this includes PR, OWP and TRP and all others.
If you try to enter Canada you will be asked about previous convictions or impending court dates, which you'll have to answer truthfully especially if you're planning on becoming a PR in Canada. Unfortunately the chances are you'll get turned away at the border. With immigration it seems that you're guilty until proven innocent rather than the other way round, and CBSA will probably turn you away as a potential flight risk (disappearing once you're inside Canada). If you really are wanting to make Canada your home then it probably isn't worth trying as it will cause more problems later.
My suggestion to you would be to proceed with your planned PR application. You will also need to include a Humanitarian and Compassionate submission (which has the ability for you to potentially overcome your current situation, even if you are found retrospectively guilty) in this you will need to provide a detailed account of the incident (accident) and everything related to that since. For instance copies of the original trial details, police reports, current action being taken against you etc etc. Also, you will need to emphasize how a negative PR decision will adversely effect you and your partner. This is really important for a successful H&C. Include personal character references, job references, details of any volunteering; basically highlight all positive aspects about yourself and try and show that you won't be a danger to Canadian citizens and that one potential single mistake is not typical of your behaviour. Provide as much information as possible and be as transparent about it all as you can.
Basically a Humanitarian and Compassionate submission allows the visa officer looking at your application to weigh up the benefits against the negative points, and they will have the ability to override the usual PR refusal for criminal inadmissibility if they deem you as not a threat. If you are going to go down this route collect as much evidence as possible to testify to your usual good character to submit with your application. You may also want to submit a 'For Information Only' rehabilitation application with your PR.
You can only officially apply for rehabilitation 5 years after the sentence for your conviction is spent, but you can submit it 'For information only' which shows the Visa office that you plan to apply to be rehabilitated when the timeframe allows.
Another possible line of enquiry is to check with Canadian law as whether it would be legal in Canada to revisit a case in which you've already been acquitted. The crime, court proceedings and sentence need to correlate between Canada and the country that the offence took place. If it would be unlawful to take you back to court after acquittal in Canada then you should be ok. If this is the case then this will need to be clearly explained in your application.
I'm guessing you have a good criminal lawyer? Because trying to get the prosecution to drop the case would be the ideal outcome... this is would be your best chance for a smooth PR application, and I would be focusing my energies on getting these new charges overturned somehow. If its been done once then it could happen again... unless there's new undisputable evidence come to light.
Another point if you're desperate to get to Canada would be to submit your OWP (or TRP - more likely to succeed, see CIC section on criminal inadmissibility) along with your PR application explaining that you'd like to be in Canada while this is being dealt with.
They are all long shots, CIC really don't like potential criminality, but it is possible to overcome without an appeal. But be warned it will take much longer than the usual advertised process times if you decide to go down this road.
I have been through this myself... my PR application has taken 18 months so far... However a decision was made on my case on Feb 9, but they still haven't notified me what the decision is yet, so I cannot tell you whether this has been successful or not at this point! I hope and pray that I don't have to go down the appeal road, but I will if I have to!
Also I don't know how good your immigration lawyer is, but my advice is don't get a standard immigration lawyer. You will need someone that specialises in H&C, criminality and appeals.. I had to sack my lawyer of 2 years (she talked the talk but was totally out of her depth with such a complex case) and have now retained a specialist in this area. Using someone based in Canada is advisable too, as they are generally far more familiar with Canadian case law than their European counterparts.
Good luck, it is a nightmare, but it is possible to overcome with hard work and determination!
