I agree that there are differences in liveaboards. I will give you my take on the Aggressors, where I tend to dive also as a solo traveler.
1. Equipment - since liveaboards tend to attract more experienced divers, most divers have their own equipment. The Aggressors do have rental gear. BUT the selection is limited. Also, since the boats are remote, if a piece of rental equipment needs repair, it will not happen right away. MY SUGGESTION - negotiate a rental with your LDS (at least where I live, they rent by the week anyway). Count on the liveaboard rental gear for emergencies only (you dropped your fins over the side). DEFINITELY rent a computer. In many locations your dives will start on a wall, but finish in the shallows playing with rays, looking for juveniles, ... Computers are excellent for these "multilevel" dive profiles, and will give you plenty of bottom time for your later dives. Both DMs and more experienced divers will help you with your dive planning if you ask them to. Soon enough, you will get a feel for managing your tables/computer.
2. Dives per day - the Aggressors that I have been on (Fiji, Palau, Belize, Cayman) target 5 dives per day, with exceptions for special days that have a deep dive (Blue Hole in Belize) or a shore excursion (Villiage visit in Fiji). The schedule is roughly:
Breakfast
Dive #1
Sweet snack
Dive #2
Lunch
Dive #3
Savory snack
Dive #4
Dinner
Dive #5 (night)
Hot Chocolate
Sleep
Of course, not everyone does all the dives (except maniacs like me
). Some people don't enjoy night dives, or like to have wine/beer with dinner (once you drink, your diving is over for the day). Some just get worn out! Most people do at least 3. One reason that people do more is that it is so easy. No lugging gear onto and off of day boats. Just suit up and go! HERE IS WHERE LOCATION AND TYPE OF DIVING MATTERS. In some locations (Palau), diving is done from a skiff. That means dive times are regimented. Other locations (Belize, Cayman) the boat stays at one place for half the day. You can do 1 or 2 dives ON YOUR OWN SCHEDULE.
The DMs DO NOT babysit you - you are responsible for your own tables/computer planning. On the other hand, IF YOU WISH, you can buddy with the DM on any dive. At least one DM will be in the water on every dive. Often, you can buddy with another single traveler whose experience and dive style matches your own. Also, most of the more experienced divers will agree to buddy with you a few times if you ask - just BE HONEST about your experience and concerns. Even though I dive solo most of the time, I had the genuine pleasure of taking a diver on her second dive after certification in Belize (she went with a DM for the first dive.)
When not diving, people read, watch video, lie to each other telling diving stories, sleep, eat, sleep, eat, sunbathe, eat, screw up their camera, eat, sit in the hot tub, check out other people's gear, and otherwise just mellow out.
My personal opinion is that a liveaboard is the preferred way to travel when going alone. You don't have to worry when to eat - you eat when they serve. You don't have to worry what to eat - you eat what they serve (and lots of it). You don't have to worry about eating alone - everyone eats together. All you have to do is decide when and how many times to dive.
Let me know if you have any more specific questions.
Cheers,