Someone cannot hack your Facebook account just by having you accept a friend request. Accepting a friend request involves no mechanism that would enable hacking. That said, accepting friend requests opens communication that could be used to try to trick or hack you later.
You cannot directly view EXIF data on a Facebook photo. Facebook intentionally removes this data from all uploaded photos in an effort to protect privacy. You can still get some metadata related to the photo by looking at the post’s metadata. Or, you can ask the uploader about the photo directly.
Technically speaking, it is possible for someone to brute force attack a Facebook password.
Practically speaking, it’s probably the very worst way to try to hack a Facebook account. Facebook does employ industry-standard security measures that more or less render brute force attacks meaningless.