I can't help with the prefolds and covers but I can tell you what I use and why. I am also new at this.
My baby is 2 months old and 14 lbs.
During the day I use mostly Flip covers. Flip covers are one size and you can use either an insert in them or a prefold. I have both and prefer the flip stay dry insert. Flip covers are considered hybrid diapers. As long as there isnt poo everywhere you can reuse them. I usually get 2-4 uses out of one cover before I have to change the cover. I just remove the dirty/wet insert or prefold. Wipe out the cover. And put a new one in. My DH totally favors the Flips and we use them when we are out. We just throw and extra cover and some inserts in the bag. (we also have some Econobum covers but I really don't like them. They are sort of like Flips but the quality is cheaper. It may be good to have a few on hand to use if you are washing your Flips. I got mine for $5 a piece as seconds on www.cottonbabies.com)
For naps and at night I use pocket diapers. I have Fuzzi Bunz, BG 3.0, Kawaii, and Thirsties Duo. I wanted to try different kinds. So far I like my sized FB best but I also LOVE the Kawaii diapers. The Kawaii's are so soft, one size, and only about $10 for the diaper and 2 inserts. For naps I also double the insert. You can either put a second insert in, or stuff it with a prefold and insert. I also bought some Joey Lil Bunz hemp inserts that are really absorbable for overnight.
I have 4 Bum Genius Elementals, one size, AIO. They are ok but honestly I dont reach for them often. They take about 2 hours to dry in the dryer on low and this drives me crazy!
Anyway, my suggestion would be Flips with prefolds/inserts, and pockets. I wash every other day and have the following:
6 Flip covers (although I could use a few more)
12 chinese prefolds
12 Flip stay dry inserts
8-10 various pocket diapers with Microfiber inserts (Fuzzibunz, Kawaii, BG 3.0 or 4.0, Thirsties)
4 hemp inserts
5 fleece liners (I use these with the Bum Genius Elementals)
4 Bum Genius Elementals AIO
1 large wet bag for home
2 small wet bags (one I keep clean and put all of the clean dipes in when I am out and the other is for the dirty ones while I am out)
You also may want to think about cloth wipes. I use all the old baby wash cloths I had laying around and make my own solution with water, some baby wash, and a few drops of baby oil.
I usually order from www.cottonbabies.com because they have free shipping. I also go to www.kellyscloset.com