Place Linked what file format to save

"One question, please. When using Place Linked, Is the Images loose resolution, or you are Editing in the Original resolution."

You need to step back and look at what is happening when you use place.  It is more complex the most know.

Place creates Smart Object layer by default. 

There is not much difference between linked and embedded place smart object.  One has an embedded copy of and image file that is independent from the Placed image file the other has file link to the placed file.  If that file is updated when you open a document the has a linked smart object layer to that file Photoshop will  update the smart object layer render new pixels and apply the smart object layer's associated layer transform and apply all the layers smart filters. 

 There are many different kinds of object a smart object layer can have. Basically I would state there are two classes smart objects. Photoshop Supported objects and none Photoshop objects.  Photoshop Supported object are like A Photoshop layer, a collection of  layers and layer sets sets and Image files support by photoshop.   There are other image files that can be placed into photoshop document that Photoshop does not directly support.   Camera Raw Files and Vector image files like .svg and .ai.  I you open one of these Smart Object layer object by double clicking  the Smart Object Layer content thumbnail in the layer palette.  The Object will not be open by Photoshop. Instead Adobe Camera Raw Plug-in or a vector image editor like AI will open the layers object. 

Place special cases placed vector imaged and create what adobe calls Vector Smart Objects.  While there are not vectors in Photoshop for the object the layer scale as if there were vectors for Photoshop imports the Object vector file for the scaled resize.   None vector smart object layers are resized like raster layers via interpolation.

Smart Object Layer have Pixels rendered for their content which are hardened and can not be changed by Photoshop tools.  These Pixels are transform by the Layers associated layer transform  for the layer pixels and may be filtered by smart filters.

Place has an issue when it comes to rendering the hardened pixels for the smart object content.   Place will resize the Place image if the image files Print resolution is not the same resolution as the current document current print resolution setting.   The image in the object will not be the image in the file it will be a degraded image either larger or smaller then the image in the file.  If the Object rendered harden pixels will not fit on the document canvas if you preferences has resized during place.  Place will Scale the Layers  associated layer transform so the layer will fit on canvas.   If you  are concerned about image  quality you would be better off  Pasting in you image the converting the Pasted in Layer to a smart object layer.