You absolutely require both. Well, you can try and go it alone but it would not be wise.
Our Attorney has paid his own fees many times over in time saved, doing the right thing, knowing the right people, assisting with negotiations, and having patience and knowledge to work through the reams of documentation for company preparation, cedula preparation and so on. The challenge is to find an honest and reputable attorney and I would recommend the practice of Guzman and Associados. You can send Fabio Guzman an e-mail by searching through the legal forum, finding one of his mails and clicking on the e-mail icon.
In the DR your books need to be prepared by an accountant for tax purposes.
If you will be bringing raw materials in, and exporting, you also need to be friends with your shipping agent and your customs broker.