There is no way of knowing how accurate the research is at those sites or any other site. one can only hope, wish and pray that the scientist/ceo's are honest....

That said, a meta study was conducted back in 2015 and found that over 60% of all biomedical research could not be repeated any ways. Some argue this is because of fraud on the part of the researcher , or just the inability to geting the equipment to repeat the study. Regardless its not good for science . its arguably not science if no one can repeat the study. Its just becomes statistical noise and makes research that more difficult.

Regarding mice dna similarity to human dna. Some recent research indicates that percentage could be as low as 70% . just depends on who you ask and what criteria was used to get the numbers. But as more research is done it seems the percentage is going down.

The other 5- 30% of dna that is not identical to human is unknown or not understood. But im sure its important for the mouse to have:)

By splicing the dna of mice and observing what happends to them. Since 95% of mice dna is identical to humans it gives biologist a good idea on what will happen to humans with the same mutation.

Surveys and statistical analysis of human dna is also used to identify if certain genes are responsible for certain traits. 23 and me Is a company that does this.