(1) can a company, after sometime, charge me again with a similar or identical offense but with another set of items in question? if yes, this practice can go on indefinitely? - Yes they can charge you again, kasi think of it this way. If something prevents the company from charging you then you can steal indiscriminately.
(2) is a preventive suspension legal even if in the initial investigation, the accused employee was not present or not questioned? - preventive suspension is not punitive, it is not a punishment. It is meant to prevent potential losses to a company while they carry out the investigation. so yes it is legal as long as it does not last for more than 30 days