A few problems with my first city

[Quintus5 2]

Hello, I'm pretty new to C:S, and starting to get a hang after having played SC4 and CXL years earlier. I used to have an account here but forgot the username and password...

I'm building my first city and I'm running into trouble with demand. Residential demand is always sky high, and whenever I zone for residential, people move in quickly, even if I zone them right next to the industrial zone, with no schools, parks etc. Commercial demand is around 50% and occasionally I see a building abandoned, and industrial demand is <10% and industry buildings get abandoned all the time. My industry right now is smaller than it was with 1000-2000 people and I have 5100 people right now, but apparently there's no demand for it even though nearly the entire city is residential. From city statistics graphs:

Residential: 4813
Commercial: 800
Industrial: 516 (topped out at 724 around the time when cemeteries were unlocked)
Employment percentage: 97.5%

A second problem that I have is with forestry industry. I created a specialized forestry area and it's good enough to get Level 3, but it's consistently losing me money. It's not a lot, just the building upkeep, but it's either not generating profits or sometimes it just barely evens out. I've got about a dozen tree plantations, one paper plant and half a dozen sawmills, which I'd hope would at least pay for itself! When I open up the industry overview, the chart numbers are:

Acquisition: 29 tons, all own production
Raw forest products: 22 tons (where did the 7 tons go?)
Paper: 4 tons, output 8 tons (1200 money)
Raw forest products output: nothing
Planed timber: 18 tons, output: nothing!
Upkeep: 1416
Total profit: -216

Also, I thought forestry industry would do something with the natural forests, but apparently it only uses the plantations, even though I've painted the industry area over nearly the entire natural forest on the starting tile. Why are then natural trees colored under the resources view?

[Quintus5 2]

Ok, it seems that the bunch of warehouses I had plopped earlier were the problem for forestry, after setting them all to "empty" forestry seems to be turning a tidy profit.

Also it seems that tree plantations produce more units when built on areas that were occupied by natural forests, answering my third problem.