The Florida company I work for used to give employees a 30 minute lunch break and two 15 minute breaks each day. Two years ago they switched to a 45 minute lunch break and one 15 minute break. If an employee takes the full 45 minute lunch break, they add 15 minutes to your time card so you still get paid for an 8 hour day even though your time card shows 7 3/4 hours. However, my department is understaffed, so I usually just take 30 minutes for lunch and then clock back in -- so my time card actually shows 8 hours. It seems to me that if my employer gives 15 minutes to some employees, then I should get it too. Am I right? And would this be considered overtime? Over the 2 year period, this would amount to over $3000.

Secondly, I recently worked 2 hours of approved overtime but was not paid for it because I forgot to get my supervisor to sign my timecard. Is this legal?

No, they do not have to treat employees the same way; they just have to treat them legally, which they are doing in your case. You are only legally entitled to overtime pay in Florida if you actually work in excess of 40 hours in a workweek.