Is bias setting necessary on matched tubes?

Yes, the bias will need to be reset. Make sure the bias pot is turned all the way down before turning on the amp. Let the tubes warm up for 10 minutes and then bring the bias up slowly to the recommended settings. With new tubes, check the bias again after a couple of hours playing time and again in a weeks time. Enjoy.

yes, and they will sound different at different bias settings.

Unless your amp is of the "audobias" type (primaluna is one brand) then you will have to readjust the bias. Matched tubes just means that they are very similair in terms of operating characteristics. Important! If your amp has only one bias adjustment for each channel then it's recommended that you ONLY buy matched tube sets and replace them all when one goes bad. RAM tubes website has a good primer on matched tubes.
Cheers!

Only if you have a fixed bias amp, if you have a cathode bias amp then the tubes will be self-biasing and no bias controls or check points will be present on the amp.

If the amp has bias controls and there are individual controls for each tube, matched pairs of tubes, while desireable, are not necessary. If the amp has one bias pot per pair of tubes then each pair must be matched to prevent current hogging by one of the tubes, leading to premature failure and asymmetry of the waveform.