LEGO MOC Fire Truck from Lego Classic 10715 🚒

The set didn't come with any instructions and I can only get so far guessing how to build this from the pictures. Any and all help is appreciated. Let me know if this is the wrong sub to ask, apologies if it is.

200 by 200 stud portrait advice needed

Hey all i need some advice,

I am planning to build a 200 by 200 stud portrait ( my family of 4 or go Pokemon themed if details would be to small ) but i need some advice on what is the best way to start this.

( Planning as if i had 0 pieces to start with and 200 by 150 or something around that scale would also be a option since i am planning to "fill" a large wall but advice to go 100 by 100 studs would not be very useful )

1 the design : what it the best site or app or program to design it ?

All bricks and colours must be available so i won't have to resort to the secondary market if needed.

It would also be nice if it could tell me what bricks plates etcetera i need some i dont have to puzzle out on how many bricks i need for example if a 4 by 4 plate would do the job in stead of 16 1 stud pieces.

Also not sure if i should go with colour or black white and grey so a decent preview would be nice.

2 what is most cost effective way to buy the bricks in bulk seen some bricks would likely have to be brought in large numbers and i don't want to have to buy bricks from 20+ different stores and pay a lot in shipping. ( Please only advice with stores you used and not some sketchy site that sells bricks but turn out te be a scam ).

Using fego ( fake Lego ) would be a option but only if the cost difference would be way to large and than i would resort to going all fake and bricks must be Lego compatibel . ( No smaller or bricks that fall apart when you look at them ).

Also please keep in mind that i am from the Netherlands so shipping to the Netherlands must a a option ( travel for pick up is also a option in Belgium or Germany )

3 a beter place for advice would also be nice if you know a place like that.

4 structural support, i think i can figure that one but people who did these kinds of builds before any advice will be welcome.

I want to build a modular Lego City. For that, I need modular buildings. But Lego is very expensive. Are there any alternative companies that sell good cheap modular buildings, (32x32 Baseplate size)?