Your program needs to be able to do a combination of searches. The importance of sourcing your information cannot be stressed enough. Sourcing your data is good practice, and should a conflicting piece of information come along, it allows you to make an educated decision as to which piece of information is more likely to be correct. The exchange of information with a new cousin also allows the cousin to confirm your information, and you to confirm theirs. As to how much data the program can store is up to you.
Many programs allow one text field for biographical text which prints in reports.
Some other programs may allow more than one field - one for biographical text, and another for sources or research notes. Research notes are extremely handy for noting what resources you have checked, or ideas for future research. For most people, this will be sufficient. If you want more fields than this, then you should be looking a the top level programs, such as The Master Genealogist which is event based, and gives you the power to create unlimited events for every person, and to create your own events. Exchange of data with a family member.