There is an "device rating table" tucked away on 214. Anyway most drones are rating 3 while combat type ones are rating 4. Meaning that all their matrix stuff is that rating. I generally consider rating 3 to be "free" and 4 to be a common upgrade done by security agencies(upgrade hardware and software like a comlink).
Upgrades that would be strongly advised would be analyze to prevent hacking. Also in the FAQ (and in the missions adventures) firewall isn't limited to respons and system the way other programs are.
So it's very common in play (like if the NPC has a steel lynx or something) to have a drone with 4's in most ratings but a 6 firewall and only admin and security access. (meaning the threshold to hack on the fly is 9).
On a drone pilot is used instead of system and is described as a special type of OS, which, while unclear, I just treat pilot like an agent that doesn't take up one of the slots of programs that can run before response goes down and that can't go cavorting out in the matrix and means that the drone can't be used by a player as regular comlink unless a system program is loaded on it.
Anyway so at rating 4 it gets 4 programs. Likely maneuver, target and clearsight autosofts and analyze to catch people trying to hack in on the fly. You could also store a copy of an attack prog that it can swap in for analyze or an autosoft to attack an intrude. But first it will try to terminate their connection via p223. So with firewall 6 +4 for active alert and pilot rating 4 it would roll 14 die against the hackers exploit +hacking.
Note that a PC could of course upgrade all of a drones stuff to 6 once play has started, backing up the software in case the drone gets blown up. However the rating 6 hardware cost 8000+whatever you pay for signal, which is more than the drone cost in the first place. Which is probably why corps tend to not go much over 4 or the default 3 for drones. Because after that (p321) the prices of things start shooting up.
Also note that by default most drones don't have any autosofts.
So, in summery.
An off the shelf drone comes with rating 3 response and firewall, but nothing else that isn't in the drone description.
After that upgrade as you want like a comlink and buy programs to load as you will. If you want to spice up buy drones have the standard packages from different compaines have different bundles of hardware and software for a reduced price.
For example clearsigh 3 and maneuver 3 would normally cost 1200 for the pair. But maybe you add them into this months shaiwais special, plus and upgrade to signal 4 for only 1000 over list! This is sort of what they did to spice up firearms when all the pistols have the basic same values. Just toss in discounted smartlinks and lasersights or what have you.
EDIT. People posted while I was typing and doing other stuff. But at least I've got page numbers. And tried to explain how it fits together. Probably just confusing the poor guy.

EDIT#2: I had a little typo and made it look like pilot and signal start at 3 as well, when obviously they are whatever rating is given in the drone description.