I've MySQL running on my small machine set up with MyISAM since it's default tables. Now I wish to request couple of of questions:

1) Basically alter the default table to InnoDB within the configuration file (my.conf), obvious the log file and restart mysql, would that harm any one of these database or tables?

2) Basically alter couple of tables' engine to InnoDB while using following command, would affecting its data whatsoever?

ALTER TABLE table_name ENGINE = InnoDB; 

3) Could it be smart to keep couple of tables as MyISAM (for read) and also the relaxation as InnoDB (more for choosing data) or perhaps is it preferred to choose one engine for the tables within the database?

2) It'll only modify the internal representation. Nothing that you'll notice around the outdoors.

3) It's a perfectly wise decision, whether it improves performance.

2) You are able to mix database types. i.e. innoDB and MyISAM. 3) innoDB allegedly keeps data safer. It may be the default on latest versions of mySQL.