It's never too late to do cloth diapers. (Well, maybe starting at 2.5 years old, might be a little on the late side, lol).
I would strongly suggest that you go to a natural baby store (google "cloth diapers" + your city/state). Contact the store(s) and ask if you can come in for a one-on-one to see the different styles and options. That way, you'll be able to see the various options & try them out (on a doll, not on your baby :). You could probably also take one or two of the diapers & covers you have and ask them how to use them.
In terms of ease of use, All-in-ones are probably easiest to use---the cover & the absorbent diaper part are sewn together, so when it gets dirty/wet, you just toss it into the diaper bin. However, they are the most expensive option and they take a long time to dry (mine often have to go through a regular dry cycle plus another 20-30 min additional dry).
Pockets, which are a cover with a permeable layer next to the baby's skin & into which you slide an absorbent material in the pocket, are really easy, take way less time to dry. You do wash them after every wet/dirty one. They are about the same or slightly cheaper than AIOs.
Fitted diapers are the absorbent part, sewn into the shape of a diaposable, and fastened either with snaps or velcro. Over the fitted, you need a cover. The cover can be reused for more than 1 diaper change (my rule is: if the diaper cover smells bad or it's a poopy, it goes into the diaper pal; otherwise, I rotate it out & use a different one to let the just-used one air out a bit). If you can sewn or have a friend/family member who can sew, then these are also very economical. I made some before DS was born, and it cost me $3 to $5 per diaper (that is the cost of materials, not the cost of my time); flannel and good velcro and thread were the only supplies I needed.
The most versatile, imo, is the prefold. You can fold it into a variety of shapes, and they are very very absorbent (go with ones that called "diaper service quality). Over the prefold you use a cover.
I like Green Mountain DIapers, which has a lot of really good info on their site, as well as good prices. I got a lot of my diapers from myuseddiaper.com and diaperswappers.com. I also snagged some from Freecycle (free!) and Craigslist (cheap!). Some of the fitteds I made (back when I had free time, LOL). The rest were prefolds from Pro Raps, which offers really good quality prefolds diapers and a good deal on covers ($5.25 each for the "seconds").