How long in time and space is my orbit?
Kepler's laws govern orbits, and they are relatively straightforward to plug in and calculate yourself. There are a variety of important and less important definitions and rules involved in Kepler's laws, but the heart of the matter can be expressed in one equation.
$$T^2 = \frac{4\pi^2}{G(M+m)}a^3$$
$T$ is the orbital period of the planet; $G = 6.67\times10^{-11}$ m$^3$kg$^{-1}$s$^{-2}$ is the gravitational constant; $M$ is the mass of the star; $m$ is the mass of the planet; and $a$ is the semi-major axis of the orbit. Orbits are elliptical, but if you pretend that your orbit is a circle, then $a$ becomes the distance between the planet and the Sun.
For an example in motion; for Earth, $a=1.50\times10^{11}$ m; $M=1.99\times10^{30}$ kg; $m=5.97\times10^{24}$ kg. Plugging those numbers in
$$\begin{align}T^2 &= \frac{4\pi^2}{6.67\times10^{-11}(1.99\times10^{30}+5.97\times10^{24})}\left(1.50\times10^{11}\right)^3\\
T&=3.17\times10^{7}\text{ sec} = 366 \text{ days}
\end{align}$$
Close enough!
How far is my planet from the sun?
The Earth is in the habitable zone of Sol. If we had a stonger greenhouse effect, by having more carbon dioxide or water vapor in the atmosphere, we could be farther away at the same temperature. If we had a higher albedo, due to more cloud cover, snow, or sand, we could be closer at the same temperature. There is a pretty varied zone in which Earth could exist.
But if we orbited a star that was not Sol, we might not be able to stay in the same place. A way to figure out how far away the orbit would need to be would be to use the inverse square law based on the difference between luminosity of your star and luminosity of the sun.
$$\frac{L_{sol}}{L_{other}} = \left(\frac{r_{sol-E}}{r_{other}}\right)$$
For example, our sun has 1 unit of luminosity, and the distance from the Earth to the sun is 1 AU. A K4V star is interesting, because there is no spectral standard star for K4V. However, 61 Cygni is the standard for K5V; and Epsilon Indi is also K5V and one of the closest sun-like stars. These two have luminosities of 0.15 and 0.22 that of Sol, respectively.
Lets say your sun is 0.2 times the luminosity of Sol. Then plugging in
$$\begin{align}
\frac{1}{0.2} &=\left(\frac{1}{r_{other}}\right)^2\\r_{other}&=\sqrt{0.2}=0.45
\end{align}$$
Your plant must be about 0.45 AU from the star to be in the habitable zone of its star. Going back to the first equation, we can use a mass of 0.75 Sol to get
$$\begin{align}
T^2 &= \frac{4\pi^2}{G(1.5\times10^{30})}6.8\times10^{10}\\
T&= 129 \text{ days}
\end{align}$$
What is my rotation period?
This one doesn't really matter. Earth's day is 24h; Mars's is 25h; Venus's is 2784 hours. Up to you!
