Basically all KMB buses have stop displays, but the English names only flash once, and then stay in Chinese. Other than the Cityflyers, only a few Citybuses have them (many have the displays installed for years, but still showing "in testing"). Some of the newest NWFB buses start to have them.

The newer buses (like the gold-colored KMB ones) are low platform, so just one step to get on the bus. If the elderlies in the OP's party can handle that, buses can be very convenient as christep says. Often means a lot less walk than using the MTR.

As for self-driving, while I grew up in HK previously and visit often, it's only during the last year I've driven there. The driving itself is pretty straight forward, but GPS is basically useless with all the highrises in the city, as well as the very short blocks. Many streets are one-way and many many restricted turns. On the highways, it's extremely important to know exactly which lane to use, and often you have to switch lane exactly at a very short opening or you will end up at totally wrong place.

Road signs and designs are more British/European than US. Outside city center, many roundabouts. And road signs name the area where you're going, not the name of the road or street. Parking garages are more abundant than in years past, but they're not cheap. Also, very tight spots inside. You can only back into the spots in most garages - and nobody in HK park in their spot head-in. Another thing is that stopping and letting passengers on/off are prohibited on many main roads in the city during day-time; and they are enforced.