yes

The coronoid fossa is located on the anterior side of the humerus, which is the side facing towards the front of the body.

No, the coronoid fossa is on the lateral and anterior aspect of the humerus. It receives the coronoid process of the ulna during flexion of the elbow.

The depression in the scapula can be either one of four different structures; the supraspinatus fossa, the infraspinatus fossa, the subscapular fossa, or the glenoid fossa. The problem is that none of these articulate with the ulna. The bone you are probably looking for is the humerus, and it articulates with the last one I mentioned, the glenoid fossa.

Olecranon fossa receives when extended

Coronoid fossa receives it when flexed