How will my job security be affected if I get pregnant?

Depends on who you work for and where

no

Yep, you won't have a job for a while, and unless you have enough vacation time saved up & depending on your position (possible leave of absence.) Hopefully can afford COBRA because your insurance will lapse. You are welcome to come back and reapply (starting over,) when you are ready to return to work.

You need to read your employers policies and procedures manual.

I think it would definitely affect me moving to senior positions

It really shouldn't

You’d be protected by anti-discrimination laws and FMLA law offers job protection for those who go on leave (have been with an organization for at least 12 months and worked 1,250 hours). However, a company may hire in your absence and can make a case that having the role vacant would cause hardship. Then, upon return you could be placed in a similar role if not the same. More and more companies are moving towards a more family friendly stance though (as there is a lot of bad press for those who treat families poorly) and I would check with your HR team for your company specific policy.

Extremely! I am a Male, Christian Minister in my 60s. ????

Depends where you work. Many companies offer maternity leave, which keeps your job open for a certain amount of time.