Is it appropriate to resend resume or do follow up emails when looking for a job?

Follow your gut which is telling you that it is not appropriate to re-send resume/application. I understand that your desperation but stay positive and upbeat. If you appear desperate then prospective employers will pick up on that and you only look less desirable. It's very similar to a dating situation.

The best option would be to send your best resume the first time. If you get an interview, then send a follow up letter re-stating your skills and importantly thanking the employer for the interview. Good luck and best wishes!

Never resubmit your resume. You may always follow up with an email or call if you have a contact. For online applications, however, there is usually no way to follow up. They often have a hundred candidates for each position and will not take the time to let others know they did not get the job, or even an interview.

The best thing to do is keep applying for jobs all the time until you get an offer and accept it.

Not sure about your area. I am from UK, but I would say in any situation, do not resend your resume (I think that is what we call a CV). However, I would suggest you obtain a contact name in the dpartment of the company, and check if they have received your details. It will do no harm in keeping on chasing up from time to time, it will emphasise your determination. Maybe they have hired and it has not worked out, so it will save them from advertising again. Wishing you good luck.