No worries dude!
I think I get what you're aiming towards and can see that coming together. At the end of the day, it's fun to just try stuff and see what works so go wild with it. I used to play a lot in my early teens, but haven't touched warhammer in years and years. I got the indomitus set and decided I'd go all out and get loads of weird shit to go all out on the basing and try-hard mode for painting. It's kinda practice for a Wordbearers army I'm building.
- Not quite sure how getting torn up cork inbetween the bricks as mortar would work, but I'm sure you've got it covered :) Perhaps you might need something finer like sand?
- Coffee stirrers are a good shout for easy wood
- Wine corks work for breaking up as rocks and debris, but are too much of a pain to use for walls and stuff. I tried the available option and went for convenience after that!
- Another thing I've found really useful is actual raw cork bark, like you're supposed to put it in reptile enclosures. It breaks off into really natural looking rocks, as opposed to processed cork which has that kinda lumpy texture when you break it.
- I've only used the GW Snow effect and that works well, but next time you're running low on supplies pick up some Vallejo if only for the value for money. £4.75 for 24ml or £12 for 200ml. In particular the mud effect is great, because while most texture paints are paint+sand, that one has like little planty-fibrous bits in that just textures up real nice.
- Yeah, the fencing is a cool option and was a random pick-up for me. I was buying something else in the pound shop and saw like a anti-fly cake cover thing and my brain started whirring.
- I bought lots of terrain-y stuff from Greenstuff World in case you've got money to burn. They have this cool textured plasticard (useful if you're going for an industrial theme) and also have resin bricks you can buy in bulk if you want to skip chopping and trimming sprues.
- Basically, I just ripped off Squidmar! Also found Lukes APS, Black Magic Craft and Midwinter Minis really useful. Midwinter actually has a whole video on sprue terrain, but it's Orky which kinda suits it better than imperial industrial.
Hope it all goes well! Keep me posted as you progress!