I had to read your question a few times, but I still don't know how you intend on reinforcing the walls with rebar.
You cannot simply put rebar against the existing walls and cover them with some mortar.
For rebar to be effective, it must be embedded in the proper thickness and rating of concrete for the load. the concrete supports the weight and the rebar helps keep the concrete from failing or displacing. I really think you may need a little on site professional help here. Unless you know how to pour walls, footers etc, you may get in over your head.
It can be kind of hard to tell from photos.
Your house plans (blueprints) would tell you for sure, presuming the house was built faithfully to the plans. You really should have a good look at the plans, or get somebody knowledgeable to look at this in person. Or both.
Do you know which direction the joists are running? Floor and ceiling joists will be perpendicular to the load bearing walls (or beams!), not parallel to them. If the joists pass across the top of the wall (or beam) unbroken, then the wall is possibly not load-bearing, depending on your joists, the length of the span after you remove the wall, and the load on the floor above.
If the ends of the joists are resting on the wall or beam, then it is definitely load-bearing.
if there isn't another floor above this one, and you have engineered, prefabricated trusses holding up your roof, this won't be load-bearing. The trusses are engineered to handle the load of the roof by themselves. If they aren't engineered trusses, that doesn't apply.
Is the long common wall of the living room/dining room/kitchen directly on top of (parallel with) the long wall downstairs, and is the opening between the dining and living rooms perpendicular to that long wall downstairs? It looks like the photos might be from different directions? If so, then the common wall with the kitchen is probably the load-bearing wall, and the opening between the living and dining rooms may or may not be, depending on how the joists are laid out.
But you really should look at the plans or get somebody knowledgeable to take a look in person.
Looking purchase this house, however, want to remove the bar and closets in "red", could that whole area be removed, or are those load-bearing/structural walls? The original structure for this house was a single story and these current plans are the proposed extension, upwards. Any help will be really appreciated. 
Best Answer
No, the walls around the bar and closet do not appear to be load bearing walls, except I would not remove the North-South wall between the Kitchen and Lounge.
The dashed lines on the Ground Floor Plan indicate the structural floor framing for the the First Floor Plan (above).
As you can see, a steel beam has been added just South of the Bar area and extends over the Kitchen. However, none of the new floor joists rests on the walls around the Bar, except the North-South between the Kitchen and Lounge.