Coming to macOS from Windows

Hello, first of all, I started using a mac for a few days. Previously I'm using Windows for about 15 years and feel quite experienced with it.
I started with guides from this site and have read almost everything about macOS, but still have a several questions about which I'm not sure:
1) Is there any equivalent of page up and down in Windows? For example, if some webpage is not marked correctly, it's possible to move just through 25 lines by single keypress, of cause it's not so convenient as true navigation by elements, but if page simply doesn't contain such elements (like headings and similar), it's better than just surfing through its content line by line.
2) Is it my problem or common issue? On quite heavy pages navigation with arrows seems not so reliable: for example, when I open twitter.com and trying to surf through the feed with arrow keys, VO seems really unresponsive, and sometimes cursor randomly jumps. There also some pages, where navigation with arrow keys simply doesn't work: VO just stopping react on its pressings. Also, navigation with arrow keys seems a bit slow comparing to Windows screen readers. Finally, navigation with arrow keys not always synchronize with default voiceover navigation, and sometimes when page loaded, VO focus didn't interact with web-content, but arrows did, hence, commands like VO+CMD+H can't find next heading even if it actually exists.
3) Is there a way to change Voiceover preferences on the Login screen? For example, to use user configuration.
4) Is there something like built-in OCR on intel-based models? Something similar to NVDA+R on Windows.
5) Is there a way to disable announcing type of elements on the web pages? On Windows it's possible to turn of saying "link", "heading", "list", et cetera. Is there something similar in macOS? It just takes more time, if screen reader always speaks type of each element on the web.
Thanks in advanced.