Caveat: I have not been there yet, but am in the early stages of researching for a trip to Madagascar in Oct/Nov 2024. Based on my research (admittedly preliminary, but perhaps ahead of yours), here's how I would respond to your specific questions:
Can I just rent a car on my own and drive around? Not sure of the road conditions
Wave enough money, and I'm sure you can always find someone who will rent you a car, almost anywhere in the world. I think your question is more about whether or not that's a wise choice. Everything I've read screams that the answer is a firm NO.
Roads are VERY poor, sometimes impassible. Most sources suggest driving on your own is only for the most adventurous (an understatement) for a variety of reasons, including: road conditions ("abysmal" is a term I've seen used a lot), security (risk of robbery), and time (you'll be going v-e-r-y slow in many areas). If you really want (need) to get somewhere by road, you can and probably should hire a driver from a local agency.
I've looked into a "Bus" across the country but the website shows
only 1 bus (day) available for the 2 months I checked
-- does anyone have transportation suggestions
I would be extremely wary of long-distance bus travel in Madagascar, especially with limited time. Bus service is limited, slow, not terribly reliable, and not without its own security risks. It's also not designed for tourists, but does its best to try to meet the needs of locals. Unfortunately, the options for public transportation in the country are quite limited and generally do not work well for tourists. There are a couple of train lines, but like the roads, though still nominally in use, they are legacies of the French colonial times, and have been all but abandoned since the French left in 1960 (no maintenance and in terrible shape).
For context: Madagascar is one of the poorest countries in the world. While it has incredible wildlife, scenery, and great national parks, all the logistics - and lack of functioning infrastructure - make it a difficult place for a casual tourist to drop in for a few days. Tourism is definitely a part of their economy, but most visitors tend to be big-spenders who stay for long visits (typically for weeks, because that's what it takes to get around). There are some touristy places that are easily accessible from the outside world (international flights in and then back out) but getting around within the country can be daunting, and flights are stunningly expensive. Many people fly from point to point (because the infrastructure is so bad). Most are on organized tours (usually quite expensive).
In short, if you have deep pockets and want to spend weeks there, it can be an awesome destination. For a short trip, you are going to be very limited in where you can get to. Expect many tourist services (well-organized tours, for example) to be on the expensive side. If you are traveling independently, it can be very cheap...but it can also be very, very rough, and as dysfunctional as developing places can be.
5 Days seems like a tragically short amount of time to me. I'm looking at 2-3 weeks and with that I'm finding it difficult to string together a basic itinerary with more than 2-3 locations. It's got plenty of challenges - this is a very poor, developing country with bad infrastructure and widespread, deep poverty, even by the standards of many other African nations.
Best guide book is Bradt's "Madagascar". Go get it today and start reading. Hopefully your trip there is not coming up soon and you have plenty of time to try and optimize the days you will have (first thing I'd suggest is: find some way to be there for longer than 5 days, and plan on spending more than you would like). It sure looks like a wonderful place to go, but is not exactly Easy Travel.
Hope some of that helps. Good luck.
