Address your boss, CTO, or even the CEO of the company with his first name. Do not call them "boss" or "sir."
Most people come to work early and leave on time. We are in the IT field, so, it may not matter when you come and when you leave. However, you are expected to be present when you are needed for meetings or other teamwork. As a full-time employee, you are required to work at least 40 hours per week.
Nothing specific, wear some decent dress :)