Is std passed from hand touching genitals to touching other partners genitals?

Sometimes. STDs such as herpes and HPV are transmitted via contact of the skin and so you have to be careful. Condoms are helpful but not 100%. It's important to have a conversation with your partner about their risk when engaging in sexual practices.
Yes, its possible. STDs can be passed this way. Best wishes!
Yes. Yes...basically spreading antigen (virus mostly but can not completely rule out bacterial too) to u effected mucous membranes.