Below are the differences between each BIAS series product:
Bias FX 2: Wide variety of amps and effects, and allows very flexible configuration. Also features things like Guitar Match, Looper, and more.
Bias Amp 2: In-depth tweakability for only the guitar/bass amp section. It can be customized into your own unique amp, with an additional Amp Match feature. It doesn't have effects.
(Bias Pedal: A pedal equivalent of the Bias Amp. It allows you to tweak and fully customize your own unique distortion, delay, or modulation pedal.)
It's possible to integrate your custom amp built-in BIAS AMP 2 into BIAS FX 2. However, BIAS AMP 2 is certainly not required to use BIAS FX 2, which contains many great amps already, not to mention the thousands of amp options already in the BIAS FX 2 ToneCloud.
Please refer to the below links for comparison charts:
BIAS FX 2 Comparison Chart
BIAS Amp 2 Comparison Chart
Technically, you need an audio interface to plug the guitar into. By doing so, you can play and record through the audio interface with BIAS FX 2/Amp 2.