Thank you, Javier!
Yes, the share capital can be paid in instalments. If you have multiple shareholders then the payments will come in over time from different people anyway. I would recommend just marking each payment clearly as share capital instalment 1, 2, 3, etc so it’s easy for the banking provider to see it all and issue the certificate of proof.
It’s completely up to you what salaries you draw and when, including before registering share capital. However, dividends can only be drawn after share capital has been registered. The main difference of course is that dividends are taxed at a lower rate.