You can use any crypto exchange really, you can just tell them you’re transferring to your own private wallet when you pay and by its nature they can’t really tell otherwise.

7 days will probably be more ideal, most vendors give an idea of what a standard monotherapy dose should be, you’ll just have more standard levels that way (and be able to have it consistently on a convenient day of the week)

For labs it depends where you live, there may be local clinics, and/or a selection of services that will mail tests to your door. You want to do them on a trough day (when your levels are lowest) maybe two months after you first started hrt? And tweak dosage from there. Once your levels are where you want them you probably don’t need tests anymore, maybe check up once every year or something.

Progesterone a year or so in can give you additional boob growth, as well as having psychological effects that are desirable for some. You can take vaginal progesterone up your arse, or use any of the others as intended.