How to design in 3D? as a newbie?

Hello
I'm completely foreign to 3d design, but looking to design prototypes to print in 3d. I'm physical therapist and have many ideas to create adaptive equipment for people with disabilities, however I need a platform to design these models. My questions are

1. Which software do I need to create a 3d model to scale size and print in 3d? an example of an idea to print would be a type of mug with a special type of handle

2. How do I learn the software? is this something I can learn on my own.. or would i need to attend a school ?

3. With regards to the actual 3d printing, I can outsource the printing to a company?

thanks

What you really need is a CAD modeling software to actually design equipment to precise specifications. Try Autodesk's Auto Cad. I believe you can try it before you buy it. Be prepared to learn a lot of technological jargon as most professional software is quite expensive and requires subtantial training to master the software.