I will answer your question however as a suggestion I also suggest reading up the super helpful "Manual" when working with any behaviour for the first time.
Physics cannot be mixed with any other movement or collision based plugin. The effort to do so does not equal the result. It's a situation that you can't it's a situation that you can get the result easier by either using physics or not.
Physics doesn't really have a speed limit outside of natural friction.
Solid is not part of the Physics model it may sound like it does. but it does not.
If you want a non moving physics object. create an object with Physics then set the property to "Immovable"
Other wise Solid and Physics just don't mix.
The other problem is that Physics doesn't always reproduce a 100% reliable same time occur. Especially with other factors. My suggestion don't use physics. Learn to use Bullet. Bullet has gravity too and it more reliable.
Physics is when you really need some authentic simulation of numerous objects. Say like Angry Birds.