Visa: As Swiss passport holders we get 90 days for free
Carnet de Passage: As we travel with the CdP we used it but you can also get a temporary import permit (TIP) at the border. Be careful with the CdP stamps when you travel in the SACU (Southern African Customs Union). You need to stamp in when you enter the union and then only stamp out when you leave it (therefore not at every border). The problem is, that a lot of people working at the custom offices have no idea about it and therefore do it wrong.
Insurance: You pay that when entering the country
People in Botswana are super friendly and very well educated. Most speak English fluent and the crame rate is almost cero.
Here some very country specific information:
You can get money easy at ATMs but its good to bring in some Rand or USD to get a start in case the first ATM does not work and also to pay the fees at the border.