@KiwiMiss...no problem...LOL!

Sigma makes lenses that have mounts for most brands.

The Nikons allow you to choose from 3 types of metering, 1) Matrix, 2)Center weighted, 3) Spot.  They also have the ability to customize the size of the center weighted area in the menus.  Please check the specific model that you are interested in as features may vary from model to model.

Many types of RAW software are available...some makers bundle them with the camera, some don't.  Some are available for free on the net...some not...some are bundled as plug-ins to image editing programs. RAW software is something you don't need to use at the outset...You can always get it later...you may want to get comfortable with the camera first...shoot HQ JPG's...many folks never go to the RAW stage by choice.

Just having a coffee here myself right now.....have fun in your camera quest!

In youth, we learn....with age, we understand.