Firstly you will need professional cleaning as you seem to have bleeding gums. With regards to the yellow saliva ; Use a tongue cleaner to clean your tongue regularly. Drink lots of water to keep yourself hydrated. Brush twice daily and use a mouthwash like Listerine or Hexidine daily at night post brushing. Once the professional cleaning takes care of any deposits , your oral cavity should be back to its healthy state.

Yellowish colour is an indication of the turbidity of saliva which is a function of the level of hydration of the body. Blood in the saliva can be due to bleeding gums which is a sign of gum inflammation or some throat infection. If you have throat infection you will have other symptoms also. So going by your description it seems that there are deposits on your teeth which are not removable by tooth brushing and you need a session of teeth cleaning by a process called scaling for improving your gum health. Maintain adequate hydration of the body by increasing your fluid intake and maintain proper oral hygiene which includes tongue cleaning also. Used only your toothbrush to clean your tongue and avoid tongue cleaners. Regards.