Listen to this guy, he knows what he's talking about. My medium is a mixture of coco and both FF soil brands (or whatever your favorite soil is) but I try and keep it 60-70% coco with 30-40% soil because coco is very forgiving to amateur such as myself. You should also listen to potsnob and look into making your own compost teas. Toward the last pages (I have RIU set up to view 50 replies per page so this may be different for you) look for a post by FresnoFarmer about the Kingofthehill Organic Guano recipes. The recipes that guy listed are pure gold and they haven't let me down. The only thing I must stress to you about the teas though is don't at the 5TBS of molasses like he says, that's way too much and makes it easy for bad bacteria to enter your tea mix which could be bad. Try 1TBS, 2 max and you'll get better results. If you combine coco with compost tea then you're all set. You have a medium that is near impossible to overwater and if you use compost tea, it's impossible to over-fertilize with teas. Plus coco and teas are significantly cheaper than pretty bags of soil and nutes.
As for your recently asked questions.
The bale will swell up quite a bit. Assuming you're going with the 5kg sized bales, you're gonna get about 16 gallons of coco so a 5 gallon bucket definitely won't cut it for this job.
The FFOF soil has 10 gallons in it and the Happy Frog has like 14 gallons so depends on what you're comparing to, but coco has 16 gallons and 12 bucks per 16 gallons is a pretty damn good price. I'd recommend cutting the coco with a bag of your favorite soil though for sure. I like to use the Happy Frog and Ocean Forest soils to get the best of both worlds there. I mix up 1/4 bag of each bag of soils (or 1/2 a bag of just your favorite soil) with every one bale of coco. The end result is about 20-22 gallons of an amazing growing medium that has just the right amount of nutes in it, but it's mostly coco and I get great results doing this. Put some Subcool Supersoil at the bottom of your pot and your plants will be loving you. Look into Subcool's super soil recipe as I'm sure that may interest you as well.
A 5 gallon bucket will definitely not be enough though unless you cut the bale into a bunch of different pieces and trust me, it's a pain
I would go to Lowes and get yourself one of those cheap 30 gallon trash cans for like 15 bucks. That'll be plenty of room, plus you'll have something to keep the soil good for a little while too.