Yes, other members of Slated will be able to use your profile as a way to contact you -- if they fit the criteria you set.
You can limit the people who can contact you to include only those members whom you are tracking on Slated, only members who reach a certain score threshold, or no one at all. Of course, if you opt to use Interest/Opportunity Matchmaking your matches will also be able to contact you.
When you receive an introduction message, you always have the option to accept it, ignore it, or block the sender entirely. The conversation can only continue if you accept the message, so you won't be hassled with unwanted follow-ups. The sender will never be notified of you ignoring or blocking them (it will just appear to them that you are no longer receiving messages).
See also: How does messaging on Slated work?