For your first grow you should start simple as possible, don't do a complex SOG with 20 small plants. Consider using square bags instead of round buckets, that way you can fit more soil efficiently. The buckets will work fine though. Hand water. After the first good crop, then you can experiment with SOG.
With two of the plants, you can top them to see how they bush out. The other two plants you should not crop to see how they grow with tall cola. Then if you use those strains on your next grow, you will know which method works best if you stick to buckets.
Finally, make sure you have clones ready to go in the flower room as soon as you harvest, so your get perpetual grow cycles. Best of luck my friend! let me know if you have any questions.