Volume control from reciever?

Depends on whether the line-in you've connected is controlled by the volume control of the receiver or not. Generally speaking, it's not recommended. If you're connected to, for instance, a tape out, then that line out to the line in on the CONNECT is not controlled by the volume of the receiver, it's a constant volume.

The difficulty that you run in to when you have 2 devices that can control the voiume at the same time (the receiver and the Sonos line in) is that it's hard to find the correct balance between the two.

Your receiver should be sending a line level signal to the Connect no matter what volume the receiver is set to. You can adjust the line level signal input into the Connect under the room settings...Line In...Source Input level.

Then volume control is via the Sonos app controlling the volume of your play:1s

I should like to control the volume with the remote control of the reciever. Instead I now have to control the input (turntable, cd, tuner) with one remote and the volume with another (the app) - or by the buttons on the speaker.

In Settings->Room Settings->(Connect room name), set the volume to "Fixed". Then you can use the receiver volume instead of the Sonos volume.

I only have the possibility to set line-out to viable/fixed and the line-in from 1 to 10 and 2 is preset for use with a/v? I have tried to set line out to fixed with no effect.