Hey montaser abou saada
First of all, welcome to the forum :)
Your questions are not silly at all. If this is your first time as a DP, I'd say you're already doing a good job by trying to learn different ways of doing the scene beforehand. This way you make sure u know what you are doing!
I have to tell thou, that all depends on the look, mood and tone of the film... U might want something really hard and with lots of contrast, or u might want something softer, or even something totally washed out (if this is the case, and if you're using film, a bleach bypass could give u a certain look - I hope I'm not confusing you even more... Sorry if I am)
Also, the blown out outside always depends on the amount of light you'll have inside, and the stop you will be using..
So, and if you have that kind of equipment, my first suggestion (but this is just how I like to work, other DPs might think differently), is to use your biggest light(s) as the key (in this case, the 4k HMI.) For several reasons: you u want the outside to look bright, u might as well start with a big light and scrim it down. it's easier than start with a small one, and then realize that's not enough, and you end up having to change the entire unit.
Once again, I don't know the mood you're trying to set up, but I'd do it with the 4k HMI, , maybe running thru an opal diffusion. This will stop the light down, make it less hard, and spread it a little bit inside the room. If you feel the window is too blown out, you can always use ND gels to cover them.
Don't forget that you're using tungsten stock, and the HMI reads as daylight, so you have to use a filter on the camera, which will bring you 2/3 of a stop down. Otherwise, the HMI will read really blue on the film.
I'm a contrast lover, so I'd keep the shadows hard. But if you want detail on the room as you pan, and the stop ratio is too high, because you're in a studio, I'd just lit the all room evenly, from above, and silk it. Make sure you cover the entire silk with this light coming from the ceiling. This will make your ambiance brighter for a couple of stops, decreasing your ratio for the "sunlight", and making you not lose detail as you pan.
Depending on the size of your light box, you could use it with the HMI, but I wouldn't. HMIs get really really hot, and plus, if your goal is to reflect the light, just use shinny boards...
Once again, this is just what I would do, based on the descriptions and equipment you gave me. Other DPs will think in another way. Just go there, try it, take some stills, see what better suits you, and shoot whenever you fell ready!
Hope that helps!!
Good luck!