Is the ThinkPad P53 good for CAD and 3D work?

Yes. The Quadro T2000 is ISV-certified for professional applications, and the H-series processor plus large RAM capacity suit CAD and rendering. It is not a gaming laptop, though.

How much RAM can the P53 take?

It has four SO-DIMM slots and supports very large configurations, well beyond the base amount. That headroom is its main advantage over thinner workstations.

Can I add a second drive?

Yes. The chassis has two storage bays, so you can run an SSD alongside a hard drive or a second SSD.

Is the P53 too heavy to carry?

It is a desktop replacement class machine, so it is heavy for daily commuting. It suits users who move between desk and office rather than travel constantly.

Does it have Thunderbolt or USB-C?

It includes USB-C along with USB-A, HDMI and a headphone jack. Check the specific configuration for Thunderbolt support.

Is the display good for photo editing?

The 1080p matte IPS panel is fine for office and CAD work but not color-critical. For print or color grading, a higher-end panel option is the better choice.