As someone who's been in HR/Recruiting for 15 years and recently started the path to being an RN, I can offer you the same advice that I would give any "older" applicant.
First, remember that your resume is a snap shot of your experience, NOT your life story. Meaning, you should really only include the last 10-15yrs experience if possible. If you've had 3 jobs as a CNA since 1995, then I really don't need to see the jobs you had prior to that.
Do NOT put school dates on your resume. It's not relevant to state when you graduated or got a certificate, just that you did. They may ask you later for verification purposes, but at that point, they are getting ready to hire you.
When you go in for an interview, talk about long term goals and do NOT talk about how many more years you plan to work or anything about retiring. If you are asked about it, just say that you are looking for a career position.
Even if you only plan to work for 5 or 10 more years, you don't need to say it!
If you look young, great! Make sure you dress in modern attire. Not "young", but professional.
Also, don't talk about your family. You should never do this anyway. If you're a woman, and you mention that you have small kids, some hiring managers will start thinking about childcare and sick kids and things like that. If you're older and you mention grand kids, they start thinking about how old you might be and how you may be looking to retire (trust me, it happens all the time). So just don't bring it up.
The biggest thing would be to show that you have lots of energy, drive and passion for the position.
Hope that helps! Good Luck and don't worry about that person in your class. She's just one ignorant person.