[Rom]

1. the film winder won't wind, somehow it's stuck and won't move;

Are you sure it's not already armed ?

2. the shutter button seems also stuck, because of the winder I guess;

I believe you try with the lens expended.

3. the lightmeter doesn't work: I I tried with 4x1.5V batteries, but maybe this is not correct?;

The 35 SE is supposed to receive PX27 5.6V and not 6V.

4. the aperture dial seems loose: it turns flawlessly, I supposed it would stop at every full-stop aperture (with a click or something, like the shutter speed dial);

Just under the aperture dial, you have a metal button which you can lock or unlock on the side. When you lock it, the aperture dial is flawlessly. When it's lock, the aperture is lock. When you turn the aperture dial, do you see the diaphragm moving ?

5. the shutter curtain is closed, as if it closed down after pressing the shutter button, but didn't re-open;

The shuter curtain is supposed to be close. It's just open when you take the photo.

6. the button for unlocking the lens is also a tad loose, so I don't understand in what position it must be for me to pull out the lens: the lens can be pulled out, regardless of the position of the button.

When the lens is collapsed, this button is loose. the button is supposed to be down to pull out the lens. The lens is supposed to make a small turn in clock direction in order to be locked. Then, to put back the lens, you need to pull down the button.

You can find the manual here. Perhaps it can helps.