you can get information from all the service departments from every company that deals with lift trucks and that is a start...
but they will be competing for business so what they offer and their pricing will be very important but may not be the same in how they invoice it, expense recovery is dealt with in various ways when they invoice it.
But i would try to get input from any local companies if you have the opportunity to talk to anyone from them and see how they feel about the level of service they are getting from the service providers they deal with.
Alot of people looking for service do tend to go with independents because of their cheaper labor rates but you should consider that if you need factory support it will be more difficult to get it through an independent versus getting it through a dealer.

As far as billing?
everyone has their own way of recovering their overhead expenses that and i have witnessed, there are several ways it has been done from my experience dealing with dealerships and independents both.

They all have their own way of recovering labor, parts, vehicle and fuel charges, and yes travel time which is part of the labor expense, the tech if he is fair will bill his travel time out evenly from one customer to the next fairly if he is an honest minded and organized tech.
Of course some companies may have a set travel time and fuel charge standard applied to every job depending on the distance traveled to your business which is something you both will have to sort out if you have multiple machines that are serviced at the same time. You wouldn't want to be billed the same fuel and travel time charge for every job he opens while he is there would you?

Not to mention the level of service the technician gives, they all are supposedly giving you the highest level of service according to the people you talk to at the service office but in reality not all techs are the same, their level of service vary's also depending on their level of training and commitment to their job. This area can only be determined by you once you start the service on your equipment and will depend on you monitoring what he is actually doing versus what you are being billed for. A good tech will keep you informed on every aspect of the job, so keep this in mind when dealing with them, the tech is the key to the quality and level of service you get.
dealerships will tend to have a network of technitians that could be sent to you so when you call for service you may not get the same tech every time unless you specifically request a certain tech, independents will most likely not do this and you will be dealing with the same person but the quality of service you get from him still applies to what i mentioned above about how he reports to you what he does.

hope you can make sense of all this and hope it helps in some way