Hi Simon,
Welcome to the site. I am sure you will find it more than beneficial.
In relation to yuor question, I suspect that you will get divided opinion as some model in Cad and some model in Max. My own studio models in Cad and imports directly to Max. In terms of importing it is straight forward enough. We model in a manner that reduces polygon count and rendering time, however many will solid model. If you are not able to learn it yourself in your spare time I would suggest doing a Cad course. I am sure there are plenty in your area. Once you pick up the basics you should be able to advance yourself by way of online tutorials etc - you sound like you are street wise enough with software programs
regards
Nick