is the CAP coin supply limited or its actually unlimited?
It's unlimited like many other coins. CAP inflation will get lower and lower over time though, that's because the daily amount of CAP generated by either POS or POW won't rise much over time. Added to that is the POS percentage which will gradually decrease over time as more and more coins are going to stake and a maximum POS reward of 1000 coins.
Tokens based on the work of Scott Nadal and Sunny King have 'limits' in name only.
Unlike BTC and LTC, BottleCaps do not have a hard limit on the number of tokens; this is by design to support growth of the user base. The maximum annual rate of 200% and maximum reward per block of 1000 CAPs controls the number of BottleCaps in circulation. Additionally, there is the standard deflationary aspect to BottleCaps as transaction fees paid to the network are destroyed. This along with increased energy efficiency, when contrasted with BottleCaps Proof of Work mining, allows for for greater long-term scalability.