You have a lot of topics to discuss in your post and it should generate an abundance of ideas. It’s not a straight forward proposition on how things will unfold if ebola gets into the population. For quite some time events wil be very random and you have time to figure things out.
You should leave the city well before everything goes to shtf. Everyone will agree to that, it ensures you get to your destination safely and can use a car. Deciding what triggers your move is key. You have to stick with your plan or you will probably keep putting off the move until it’s to late.
If it gets into the general public in any significant numbers so you can’t be certain if it’s safe to go into public places, you should not wait any longer for your own safety. If travel bans and restictions are imposed you will find it difficult to leave.
About those bridges. It’s getting cold so swimming most rivers will be impossible. Even in the summer time it would be a challenge not worth the risk of drowning.