Electrical – Hooking up additional outlets & lights to a central vac circuit

If you don't plan on using any 20 ampere cord-and-plug devices, there is no reason to install 20 ampere rated receptacles. Circuits rated for 20 amperes are useful in the home, because they can support more devices. 20 ampere receptacles are often not advantageous, except possibly in a workshop or garage.

No, Code says nowhere that a receptacle-type AFCI or GFCI is required; breaker-type GFCIs and AFCIs are also usable whenever AFCI or GFCI protection is called for by the NEC or otherwise desirable. In fact, circuit breaker manufacturers now offer a device that's both a GFCI and a CAFCI in the same package -- look for a DFCI (Dual-Function Circuit Interruptor) breaker.

As to your clarified question (cites from the 2014 NEC):

The refrigerator receptacle and the dedicated microwave receptacle do not require GFCI protection, as those receptacles are not installed to serve the kitchen countertop surfaces, and likely are more than 6' from the edge of your kitchen sink as well.

The DW circuit, however, does require a GFCI, even though it is hardwired, as per 210.8(D):

(D) Kitchen Dishwasher Branch Circuit. GFCI protection shall be provided for outlets that supply dishwashers installed in dwelling unit locations.

Note the word "outlets" in this passage, vs. the use of the term "receptacles" in 210.8(A) -- in Code parlance, an "outlet" is a place where power is tapped from a circuit to serve a utilization device, whether it be a hardwired device, a luminaire, or a cord-and-plug connected device, while a "receptacle" is what you plug cords into.

The disposal does not require GFCI protection either, unless its receptacle is within six feet of the top inside edge of the sink bowl "as the cord flies". (In other words, the receptacle, while not covered by 210.8(A) point 6, may fall under 210.8(A) point 7.)