4x4 is perfect with 400 or 430 hps ...thats what im using and im glad im not running 600 or 1000 just due to heat factor and because you can get that 400 a little closer to your canopy, you get about the same amount of lumens to your plants as a 600 or 1000 ... i do have another room with a 1000 in it and i have to keep it about 4 feet above the canopy so i wont burn the plants... also plants want to stretch and reach for light... so hammering the shit outta them with a 1000 tends to keep your canopy a little lower unless you have the vertical height to hike that 1000 up. Stick with the 400's .... also you get much better light penetration running 2 400's a few feet apart than a 1000 due to the light spectrums overlapping and less shadowing in the lower branches
for mediums... i clone in 1" rockwool cubes ... once they are rooted (roots at least 1" exposing roots from the bottom of cube). Then i line 4" plastic baskets with 4" coco liners and put about an inch worth of hydroton (rocks) in the bottom, (rinse the rocks well before use to get powdery dust off so it doesnt collect in your reservoir or plug your pump), then place the new rooted clone on top of your rocks and pack more rocks around the rockwool cube and on top of the cube. If a lot of light hits the top of your rockwool cube a little algae will grow which is fine and actually its a good sign. But I put a few rocks around the base of the new clone on top of the rockwool cube as to block the light off a little bit.
You dont have to use coco liners inside your plastic baskets but i find that it helps keep things stable a little better and add a little weight to the base, considering i use small 4" baskets.
also you want your waterline in your flood table to fill up to the BOTTOM of your rockwool cube... then you can flood more times per day... if you are soaking the shit outta your rockwool cube everytime your waterline floods up, chances are its holding too much water and you wont have the "best" root growth.... remember, its just as important for the roots to get dry as it is for them to be wet... roots grow and develop when they are dry to search out water
cheers!