The slime coat occurs within 14 days.
LR rubble can be purchased from your LFS from the bottom of their LR bin. Or ask your local hobbyists for some. Or use those tiny pieces you save to mount frags on. Or kill one live rock with a hammer if you must.
Filter socks, sponges, panty hose and more are one more job. I'm not opposed to them, but I don't want to clean them. Over all, I have to say my system looks great and there aren't any sponges or anything to trap particulates. After all, you do (or will) have corals that eat particulate matter, and if you remove them all, the coral doesn't get its necessary nutrition - perhaps.
I've been running sumps now for maybe 3.5 years, on 29g, a 55g, and the 280g. Typically people comment on how clear the water looks. I tend to agree - it looks great and I'm not slaving over something that needs to be cleaned & replaced every couple of days.
Keep in mind, if you have a fish jump into the overflow, it will end up in the panty hose or clog the pipe. I'd rather have it flush through and find it swimming safely in the sump rather than discover its corpse in a fouled up bag/sock/panty hose.
Every three or four weeks, I spend 10 minutes siphoning up detritus in the sump during a water change or just because I have the time, and I clean my skimmer daily. I clean the glass every three or four days. The rest is feeding, checking on equipment, posting here, working, eating, sleeping.....
You can create a bubble tower or bubble box for your skimmer, or put a Tee on the end that points up and down, with a short riser tube (3 or 6" tall) on both ends. This will let the water flow out, cause the airbubbles to rise and pop, and keep salt spray to a minimum. Or have the skimmer pour into a bubble tower if you have the room and the skimmer is high enough out of the water to do this. I usually just turn the skimmer away from the bubble trap, and this has always worked well.
The bottom line? Zero bubbles in the return section.