3 noob questions

I'm new to 3d printing and have a CR-10 coming in a week. I have 3 noob questions.

1. What exactly is Cura, and is it necessary if you have software that generates .stl files? I have and am proficient in Sketchup and Rhino3d. Both export to stl.

2. Based on it's properties, I'm hoping to print ABS. It seems bed temperature control is critical for ABS and many people recommend enclosing the unit and/or insulating under the heat bed. (I watched a few of the videos on this.) I wondered if anyone tried using computer thermal paste between the heat bed and the glass plate? It occurred to me it might facilitate faster heat transfer and reduce heat up times.

3. I intend to build bicycle parts and chose ABS for the strength and better outdoor properties. It there another filament that might be better for my purposes that is compatible with the CR-10?

1. What exactly is Cura, and is it necessary if you have software that generates .stl files? I have and am proficient in Sketchup and Rhino3d. Both export to stl.
Cura is a slicer/toolpath generator. Cura takes your STL file and converts it to G-Code (something the printer controller can understand and convert to motion, etc.)

2. Based on it's properties, I'm hoping to print ABS. It seems bed temperature control is critical for ABS and many people recommend enclosing the unit and/or insulating under the heat bed. (I watched a few of the videos on this.) I wondered if anyone tried using computer thermal paste between the heat bed and the glass plate? It occurred to me it might facilitate faster heat transfer and reduce heat up times. The reason you use thermal paste in PC applications is to make sure that there is no air gap between the CPU and cooler, as the air would heat up very quickly. That isn't an issue in a heating application.

3. I intend to build bicycle parts and chose ABS for the strength and better outdoor properties. It there another filament that might be better for my purposes that is compatible with the CR-10?
ABS degrades over time when exposed to UV light (ie. the Sun), if ABS has a suitable enough strength for your application, ASA material would alleviate the issue. If the parts are structural, consider more sophisticated materials like carbon filled or nylon. They won't print easily on a stock CR-10 though..

Pet-g is the filament you want.
Often called polyester (though that really is a huge family of chemicals).

Pet-g is much easier to print than abs - doesn't require a heated print volume, doesn't stink and doesn't require acetone. It's also not that expensive has a slightly higher glass point (when it gets soft) than abs and is chemically resistant to just about everything.

And yes you do need a program to slice your stl models.
Not necessarily cura, slic3r and simplify3d are also available as are many others.

A slicer actually does exactly what it says on the tin. It looks at the stl file and cuts it into thin layers/slices and then generates the tool path the printer follows to construct your actual print.

As a general rule Rhino3d will give you better stl files than sketchup. It just handles solids better.

Thanks for the responses. I've been researching Cura and have cleared picture. Pet-g and ASA material sounds interesting. I'll do some more reading.

yeah with nylon you really need a heated build volume.
I've made a few very small items with it, but anything of any size is unlikely to work without a heated build volume.