Can Kepler's laws apply for circular motions? (First law states planets take an elliptical orbit)
Yes, they apply. Kepler's first law states planets take an elliptical orbit, and circles are special cases of ellipses. In principle, one can also call a circle an ellipse with eccentricity zero.
The circle (eccentricity $\epsilon = 0$) and the ellipse ($0<\epsilon <1$) are two of the four conic sections; the others being the parabola ($\epsilon = 1$) and the hyperbola ($\epsilon >1$).
All four conic sections are possible trajectories for orbits with the Sun at one focus.
You can think of a circle as a degenerate ellipse with the two foci that an ellipse has being at the same position for a circle.
The equal areas in equal times law is also followed for all of the conic section orbits as angular momentum is conserved for each of them.
The period -distance law is only obeyed for the bound obits - circular and elliptical.