Script consultants are reputable and can improve your work if you can afford them. However, always have your script professionally typed and formatted. The more professionally presented, the better your chances are of getting it read. Some do xeroxing, some may ask you to make your own copies. Lawyers work with agents in deal-making.
Agents make multiple submissions.
Agents work for free unless they close a deal. They do not work by the hour. Managers for writers are becoming increasingly popular. As screenwriters cache and currency increase, writers need a bigger team and hence, will pay more commissions, just like actors and musicians. Read the trades, magazines, and on-line articles with a grain of salt.