Can I take leave of absence or unpaid leave for 6 to 7 weeks before pregnancy due date on H1B visa?

[visha]

I’m on H1b working in MA. Recently my husband got a job in TX and had to move there. I’m planning to deliver the baby in texas so that I could stay with my husband. My employer provided an option to go on unpaid leave, before delivery, which will be around 6 to 8 weeks of unpaid leave with health insurance benefits. After pregnancy, the 12-week FMLA(includes 8 weeks short-term disability paid leave and 4 weeks of unpaid leave) will start. Total leave before delivery (6 to 8 weeks unpaid leave) and after delivery (12 weeks) will be around 18 to 20 weeks.

Questions:
(1). With a letter from my employer approving 6 to 8 weeks of unpaid leave before delivery, will my immigration status stay valid while on H1b?

(2). During/after FMLA, do I have the option to resume my work only with my current employer or join a new company (h1b transfer) ?

(3). Will I be going out of status if I dont join my current employer after FMLA?

(4). If H1b transfer is allowed, what documents are required for h1b transfer after 18-20 weeks of leave?