Question about exporting models (WARNING: extreme noob inside)

So, I’m busy with creating 3d models and I want to upload them on the internet.
Now, for the questions…:

Which format will be the best to use to export my models considering that Blender, Maya, Max, etc. users should all be able to use it?

After the model is finished, should I join the different parts or should I keep them apart?

Is it possible to export it with textures and materials in such a way that users of other 3d softwares will get exactly the same as I would when they render it?

I’m not sure if I’m making any sense here, but all help will be very much appreciated.

Thanks!

obj and the textures go with you will see to files.
Joining model parts is up to you depends on what they are and are for.

Hi.
Thanks for the reply.
It’s parts like car wheels, clothes on people, etc. It seems that I should keep all the stuff apart, seeing that people will tweak, edit or animate the model. If they wish, they can join it themselves.