deep and tall not as important but the width is, but most microwaves are about the same width.

Yes, will fit no problem. May have to redrill top mpounting holes in cabinet and/or add a cross brace if tbe new mount does not match old holes.

I purchased this for my in-laws and theirs was the 1.5. It is a little deeper, but it still fit.

All microwaves are a standard width

Yes. That is a standard width, and the depth/height only vary slightly with models and manufacturers. The biggest thing is width, and like I said, 30" is the standard width for the opening. The microwave is about 1/4" slimmer (1/8" per side).

Yes, I have it in a 30" wide area

65 pounds

the panel indicates four (4)

About 65 lbs

It is right around 50 pounds. I picked mine up at the store and it had cardboard on the top and commercial shrink wrap plastic covering the rest. I don't know what they do if they actually ship the item for delivery.

5 lbs.

It comes with it. Be sure to save the top of the box that it comes in! That is the "pattern" for where to put the wall mounting holes, etc. A little confusing at first, but it really does work. The paper pattern is for the underside of the cabinet only - be sure to align it properly (front to back) or your holes won't be in the right place. Just take a couple of minutes to really compare the the patterns to the unit and it will make sense. I'm a handy lady and didn't have any trouble at all. It was a whole lot easier than my old unit.

The installation hardware comes with the microwave. If you don't currently have an over-the-range microwave, make sure there's a 30-inch-wide space (usually over your range) to mount it.

Included

It comes with all the mounting hardware you need. Previous units that I have experience with had everything from full plates that mount on the back to a "U" shaped aluminum thing. This unit just has one bar that goes across the back bottom of the unit and two screws that hold it from the cabinetry above.

If you purchase it new, it will come with the wall mount.

I don't know. ours is the same white as the unit. perhaps the lighting in the store has some effect??

It is pure white, just like the rest of the unit. If you're seeing yellow, it must be a very old display model.

Must be because It's a display, mine is white.

Our model is solid white and looks great.

See the website. Can order in SS it appears.

This oven can be vented out the back and through the wall, out the top and through the roof or recirculated back into the room.

It vents either way.

I've installed a number of Stainless Steel OTR's from various manufacturers (Frigidaire, Whirlpool, Electrolux, KitchenAid) and all of them were shipped with the ability to be set up to either vent internally or externally.
I've not yet run across a situation where I had to replace an OTR that was externally exhausted, so I can not advise on what is entailed with modifications, or extra parts that may be needed, to adapt to an existing external vent.