If you've been operationg w/out liability insurance to this point with no problems, consider yourselves lucky. Now, I'm not being critical, but I guarantee that eventually something will happen and you'll get caught with you pants down. Remember, liability insurance only costs about $500/year for around $1 million and have commercial insurance on your vehicle too. Why you ask? Not only will you cover yourself, but you will also lend yourself as a professional; contractor or subcontractor.
Just yesterday, I met with a property manager to explain our plan of attack for snow removal service and his first concern was if we were going to spend TOO much time there (unfortunately, this is a T&M job). I explained to him that since I have been hired as his professional snow and ice management contractor, I am not only potentially liable for slip and falls, etc. but the quality of work we do will reflect upon our company and his complex. Therefore, my plan was to do everything possible to ensure the job was done right and that the quality of work/timeliness would outweigh the cost. In fact, after I explained my position, he completely changed his attitude on the matter.
In regards to the average hourly rates, here in Iowa the T&M scabs work for anywhere from $30 to $65 per hour. In fact, I agree with the others that we, as professionals, should charge well over $100/hr. on average. This is why we have completely quit bidding T&M jobs; they're simply a waste of time. It's my opinion that many customers don't really care about the quality of the plowing job as long as the lot is open and nobody complains or gets hurt (cost over quality). What they can distinguish is how we present ourselves, how often we show up during a snow event to offer our services and the distances we went to ensure their satisfaction. The end result from our professionalism will be a quality job and satisfied customers.