Eu4 Help

I’ve had this itch to get back into eu4 and try for some achievements but I’ve had some issues I’d appreciate some guidance on:

How should I have my army comps as?

How should they look if I get a specific combat bonus like how there’s an infantry 15% for instance?

What’s the strategy to keep autonomy low (especially after I seize land in the beginning)

This one is a little less important but how does it work with the auto suppress rebels mechanic?

Thanks!