I don’t do it, but I know some people that do. It really depends on the level of support you’re willing to provide to your clients. If I have them on retainer, I feel like they might feel like they are entitled to send me more emails, queries, etc.
Not to sound harsh but that’s your fault. You need to be confident in what you’re doing otherwise business people will destroy you. If you do not want to do something that is completely unfair, speak up and do not give in. I’m assuming they want you to make a lot of changes and since you’re new at this you’re putting your head down and agreeing to it but quickly finding out that is isn’t quite fair.
Most lawyers should have an understanding of IP and digital law but like Chris says I would ask them to assess your business and make bespoke contracts according to your needs as a supplier of commercial services.
BTW – it is worth researching what you want to be protected against and what you want the terms of your service to be. Lawyers may take the slow and more costly path if you don’t provide them with clear direction, too.