Can blood on thyroid fna biopsy sample slides cause distortion of cell groups?

No. Blood products, cells and vessels are in every tissue in your body, so inevitably they will be present in biopsies. Special stains and other substances are used to differentiate different cells and tissues.
No. Excess blood in the sample may make it harder for the pathologist to identify thyroid cells. A 27 gauge needle (very small) is used to decrease blood in the specimen.
No. Excessive blood may create very thick smears which can be difficult to examine with a microscope. The cells themselves are not distorted.
Unclear question. Blood is normally present in fna samples and pathologists know to work around that.