new samsung device so need some help

If I delete a textmessage on my sumsung galaxy - will this text be gone? Or will it still be on the phone and possible to recover?

If I delete messages on samsung galaxy, will this textmessage disappear from both phone, SD-card and cloud? If not, what do i Neeed to to, to be able to delete it once and for all? And I also wonder what type of data the cloud system can store - can it store everything or just pictures for example? And I also wonder, if anyone have my account and username and password, can anyone who have that information enter my account and cloud without that I´m beeing notified that someone is on my account?

I also wonder how long can a textmessage be stored in the cloud system? If I dont have more data space (15 gb) available will old textmessages and previous data be overwritten by new ones? I also wonder if you can log on to Samsung cloud by a computer? Is this possible without the owner beeing notified of login attempt?

If I dont recover deleted data like pictures and messages on samsung galaxy for a certain amount of time - will this be exceeded with new data? And If I will recover deleted data on a samsung, must samsung galaxy device be connected to a computer and one must have screen code, or can anyone do this without having the phones key pasword (screen kode)?