This is all just off the top of my head, so some of this might be inaccurate, but here's what I think based on experience.

1. I don't think you can reorder devices easily. If number 2 is doable, you could hack reordering together by deleting/invoking in a particular order.

2. I think this is possible, because you can add devices from the Push. Mostly anything you can do from Push is part of the API.

3. You would have to iterate through devices looking for a device with a particular name. So, yes you can reference a device based on it's name. But at it's core it will still have a path to a device at an index in the devices list.

tahnks a lot ! useful infos. I thought about the iteration but now that i think of it it can be problematic because two instantiated devices in Live can be the same and have the same name... i thought maybe using an effect chain would help, but it doesn't seem to be possible to programmatically change the order of effects in a chain. Do you know if it's possible to get the push patch without the push somewhere ?

1 and 2 are not possible.. Even though you can load stuff from push, this isn't exposed in m4l

You can use mxj to simulate keystrokes. This will Let you cut, paste, and instantiate devices