There are several issues / solutions for your question, so I will explain them separately.
1 - In 2D, TFP is divided in tabs (Floor, Deck, Landscape, etc). These tabs work as layers, and each one has a color (that you can change in the Preferences Menu). Using the Information tab (right of the screen) you can show or hide the different tabs by selecting their names. In the first image attached, you can see that we are in the Landscape tab => go to the Information bar => Go to Landscape Visible plans menu (outlined in green) => select the additional tabs to visualize => in the image, you can see the Detail tab and the Deck tab. Therefore, while you are in a certain tab, you can select to show / hide the different tabs.
2 - The objects in the Furnishing tab as well as the lines, shapes in the Detail tab, can be placed in any tab. So you can place a chair in the Framing tab, for example, and it will remain in this tab unless you move it to another tab (Select => Edit => Move to plan => Floor, Deck, etc). These locations don't affect the 3D view or the objects' properties. You can visualize the desired tabs together or separately. For example, in the second image attached, you can see different elements located in different tabs, visualized in the Detail tab with different colors. This means that you can (for example) place the bookcase in Floor tab, the candles in the Deck tab, the books in the HVAC tab, etc. Then, in 2D, you can visualize these items together or separately by selecting the tabs as described in the item # 1. If the candles are in the Deck tab, going to this tab and hiding the remaining tabs, you will be able to select them without problems.
3 - You can select the items in 3D => if you wish to select the object in liveview, you can use the 3D selection tool (arrow icon => Live view screen) and point the desired object in 3D (pointed with a blue arrow in the 3rd image attached) => the object will be selected in 2D (pointed with a red arrow in the 3rd image attached)=> the object's properties will appear in the Information tab (pointed with a green arrow in the 3rd image attached) You can select items just on the active floor / tab. I suggest to work with liveview / half view so you can control the plan and the live view at the same time.
TFP, as any program, has a learning curve. The best way to learn the program, IMO, is practice + practice + practice => Read and follow the manual (this is important), see the videos => try to create elements not related with your project, so you will become familiar with the commands and how to develop the different components.
If you are interested, I wrote several training e-books, one of them is free
See links below (in my signature)