a) Is it better to have both http & tcp monitor on it or just one of them & why?
http monitor will check content(response code ex: 200) and tcp monitor will check the service(port ex:80) in the device.
By having both you can easily determine the issue , whether it is service or content.
if issue with service both monitor will fail, else issue with content.
Note :http monitor will do same job what tcp monitor is doing.If you frequently peforming change in server enable both otherwise http monitor is enough.
b) What is the interval of this monitor running against the pool/node?
interval: how often in seconds to send a request
timeout: how long to wait for a successful response before marking the member down
timeout = 3 x interval + 1
Set interval Based on response between server and F5.
c) will this monitor generate traffic to the end node while doing its monitor?
yes, it will.3whs and get request involved during monitoring