I met all the qualifications in Section 121 itself, but this following bit from Publication 523 states that "ALL of the following [must be] true:"- You weren't using the space for business or rental property at the time you sold the property.Technically, no...

I want to caution everyone against investing with Techvestor (techvestor.com) or related companies Scoutpads, Metallic Blue Development (MBD) and Superhost Labs.

Also metal door frames may help. 

Typically there is a metal plate between concrete and raw wood to avoid the rot.

I read a couple of books, listen to podcast, YouTube video but so much information overwhelm me, I some time I just feel like taking a metal break.

We are renovating a home in the Catskills and stuck on what railing to install on our outdoor deck—cable or metal.  

Well, it was not, the unit is VERY old, the coil is leaking (directly into the electric furnace, but that's another story, it too is about 30 years old).

A nice touch is to provide some nice metal shower curtain hanging rings already installed on the rod and a nice translucent milky colored shower curtain that fits, brand new sitting on top of the toilet tank waiting for them when they move in- so they can take a shower and not have water go all over the floor for the first few days.

The other thing I don't get is the concern over the metal frame?

It ended up costing us $50,000 in additional expenses across 25 windows because once we changed the windows, we had to bring the framing around the windows up to 2023 code - which required removing the already installed windows and reframing each window down to how the studs were strapped with metal straps down at the floor.