Riding a bike doesn't mean someone is automatically at fault, or not at fault. It depends on the facts of the accident. I have successfully represented many motorcyclists in personal injury claims and the fact they were on a motorcycle didn't enter into the determination of fault in my opinion.
Could be a case depending on whether it can be proven that the ice was an unnatural accumulation of ice/snow, like from a leaking downspout or gutter. If it is from such a man-made situation then you may have a case. If it is a natural occurrence, no leaky gutter or some such, then you probably do not have a case. The law in Ohio is tough on the injured person in the case of ice/snow. There is generally no duty to remove ice/snow in Ohio, which surprises most people. Probably worth talking to a...
In Ohio it is very, very difficult, almost impossible, to sue your employer for a work-place injury and without more info it is hard to say. You probably are limited to your work comp claim . Your work comp lawyer should be able to give you advice on this issue. If you don't have a work comp lawyer you should get one.
You didn't say when this occurred but there are strict time limits under which you must act or lose your rights. I would suggest you start by making an appointment with a good workers compensation attorney in your area and do it now because it sounds like there may be grounds to file a workers compensation claim under the law of Ohio, even if you no longer work at the same place.
You should get a local lawyer. They should be responsible for your damages. I agree the longer you wait the harder it can become to be successful. Take pictures and make some notes about what happened so you don't forget any important information. You shouldn't wait any longer as they are already jerking you around.
Generally the insurance company only has to pay the reasonable market value of the car. They do not have to get you a replacement. You can show them the receipts for the repairs and they may bump up the offer. You can also go through the salvage process if you want to keep the car but that has some headaches too. The car has to be inspected by the State Patrol and you get a permanent salvage title if it passes.