Can I screw up VB by adding tables to the DB

[samacohen]

Hi. I am teaching myself php and mysql and I would like to start adding to my VB . I have three simple questions.

1. If I add new tables to the forum db, can that, in anyway, mess up VB software. I don't think it can, but I just want to make sure. (The tables would have new names)

2. If I insert new files or folders into the vbulletin directory, can that screw up the forum?

3. Is it a bad idea to add users through my own queries, verses, say the standard registration or admin add-user form. I want to write an insert query to the user table, where I can add multiple users at once, inserting just username, password, email, & usergroup, but I am worried that I might be leaving out some essential hidden information or, because passwords are encrypted, doing it through a query might mess that up

Thanks for your help,
Sam