How Do I Begin With My New MacBook Pro 15”

You don't need to charge it first. If it still has a charge, then you can simply turn it on.

Do note, Apple has not released a 15" MacBook Pro since 2019.

All larger MacBook Pros since late 2019 have been 16".

If this is a preowned MacBook Pro, you may need to erase it before doing anything else.

Otherwise, if it was correctly restored before selling or is actually new old stock in box, just turn it on and follow the onscreen prompts to set it up.

click here ➜ Get started with your Mac - Apple Support

Yes, a 15” MacBook Air is a thing.

Depends on what kind if data you are looking to transfer

Data stored in iCloud, such as Contacts, Notes, E-Mail, Calendar entries can be synced by logging in to the iCloud Account and turning on the relevant switches in System Settings ➡️ Internet Accounts ➡️ iCloud ➡️ Saved to iCloud.

Beyond that, adding your other email accounts to the mail App, will also enable this type of content in the other relevant Apps.

For photos, you can use the Photos App or Image Capture (both available in the App launcher, or Applications folder in Finder) to transfer them to the Mac by connecting the iPad to it with a USB-C cable.

click here ➡️ Image Capture User Guide for Mac - Apple Support

For documents and other files in the Files App, you can AirDrop them to the Mac.

click here ➡️ Use AirDrop on your iPhone or iPad - Apple Support