You will do just fine in the 5 gallon bucket. I used almost exactly the same stuff for my first two grows. All stuff I could get at Walmart or Home Depot. Except I didn't have the worm castings.
Do you plan to grow from clones or seeds? Will you grow in the bucket the entire time?
If you are planning to, you will want to "layers" of soil in your bucket. The bottom layer will have lots of amendments, to feed your plant, and the top layer should be almost plain dirt so you don't burn your young roots.
Start with about 2 gallons of your MG potting mix, 1 gallon of worm castings and add about 1 gallon of perlite. To this "base" add 2 cups of blood meal, 2 cups of bone meal, 1/3 cup of epsom salts, and 1 cup of lime. A cup or two of the composted manure should be OK, but don't go crazy, I've heard it will burn plants pretty easily. Mix that all together, and the bottom 2/3 of your bucket should be full.
This will be where mot of your nutrients sit. You'll put a layer of plain MG soil with perlite and maybe some worm castings on top of this. That way, your young plant can establish roots in the "plain" soil, and when your plant gets bigger the roots will grow into the "hot" or well fertilized soil.
That should be enough to keep your plant healthy the whole time, but you may run out of nutrients if you run a super long veg time. If this happens, you'll see yellowing in your lower leaves. If that happens, you can simply mix up some more "hot" soil, and dump it over the top of the soil in your bucket. This will work as a top dressing. Or like green leave says, you could make a pretty awesome tea and just water with that.
Growing in soil makes me feel like a farmer, and it's like a fun, never-ending quest to find more stuff to add to your soil. I was able to find kelp meal pretty cheap at a local feed and farm supply store. I got some Bat Guano from Amazon, I don't know if you mess with that stuff, but I was able to find some for like $12, with no shipping charges.
For more info on soil, check out this thread.
https://www.rollitup.org/subcools-old-school-organics/44686-subcools-super-soil.html
good luck bro!