mostly dental visit is discouraged further along in pregnancy other than some coz some treatment is unsuitable to be preformed during pregnancy, it is also due to you having to be on your back for some time so might be uncomfortable. But if you are having dental issues that needs to be treated, inform the clinic about your pregnancy when making the appointment to see they are ok to see you.
Yes it’s fine. Just let dentist know you are preg. I did my scaling n polishing during second trimester.
Cleaning is okay.