How does a company hire people?

A recruiter called me a week ago and asked me some questions about my background and said he will talk to the hiring manager and then get back to me in a week. After the phone call I did a search about the hiring company and found this exact job and it was posted a month ago. Also, there were some other openings posted in August for which I might be qualified.
Today I called the recruiter for some updated information. He didn\'t seem to remember anything about me, but he asked me to resend my resume and promised he will talk with the hiring manager soon.
Can anybody help me with the following questions: won’t the hiring company directly search resume even they’ve accepted it online if a recruiter was in charge of screening? If yes, is it only for the specific job, or all the jobs? Does it conflict if you’ve sent your resume directly to the hiring company and a recruiter has already contacted you? If not, what would be the best way to get an opportunity for an interview: send your resume directly to the hiring company or push for the recruiter to get the process going?
Any reply would be valuable for me. Thank you very much in advance.