Hi, Sharasai -
ABSN programs are for people who already have a bachelor's degree in another noon-non-nursing field. Your best bet is to get an ASN (often from a community college) or a BSN (from a four-year college or university). You can certainly do an RN to BSN program; many nurses do. It often depends on how competitive an area is when you're looking for a job; some hospitals prefer applicants to come in with a BSN, but others don't mind an ASN and will pay for your BSN (or for a good portion of it).
Getting a job as a CNA is an excellent idea. At the very least, volunteering in some capacity is very helpful, but going through the CNA training and then getting valuable work experience AND earning money for school will be so helpful. Many CNA training classes are paid and then you work for the facility that trained you
As for prerequisites, these are usually college-level courses that count toward your degree. For example, an ASN is usually 60 credits. Maybe 50% to 75% of those credits will be nursing credits, but the remainder will be English, composition, sociology, psychology, A&P, microbiology, nutrition, etc. - whatever your school requires. Some people take college courses or earn college credit while in high school, either through AP classes or community college classes; those will often transfer to your college. Colleges will specify whether the prerequisites are high school or college. My school requires high school or college chemistry and biology, for example, because these are prerequisites to college-level A&P, which is a prerequisite to microbiology. They all build on each other. If you don't understand biochemistry, A&P becomes much harder.
Some classes are technically co-requisites; you can take A&P while you're taking your nursing courses, but it's a lot of work. If you get those classes out of the way first, you'll have more time to focus on nursing, which is a challenge to many students. Also, if you take A&P first before applying, you'll do better on the TEAS and many admissions departments give extra weight to good grades in A&P.
As far as how long it will take to do pre/co-requisites, it really depends on how fast you take them and how many your school requires. My school requires 24 non-nursing credits. You could easily take those over a year (including the summer) leaving you two years of part-time nursing study (ha, ha, ha - nursing is NEVER part-time! 😆) to complete your nursing courses. It's generally easy to transfer prereqs to another school; mine are from a bunch of community colleges in my state and I took everything but my two A&P classes online. You may apply to two or three schools that require slightly different prereqs, so one may require sociology, but another requires nutrition. I would plan on taking whatever each school requires so you give yourself the maximum opportunities to apply and get into schools. Plus, most of those classes will be useful or even required when you do your BSN.
Your next step should be meeting with an admissions advisor at your local community college. She will be able to guide you in your next steps, including financial aid. Please consider community colleges over for-profit schools like Rasmussen. You will save money and time by going to a local school. You can even look at the schools around where you might move and be preparing to apply to those, but have your prereqs out of the way before you move.
Good luck, and congratulations on being the first person in your family to attend college! Your community college will have lots of resources to help students like you who are in unfamiliar territory.