Can I pay my Bolivian visa fee in credit card?

No. Bring the exact amount in clean, crisp US dollars. They will reject bills with even minor rips or ink marks.

Do I need a yellow fever certificate?

Not for entering Copacabana from Peru, but if you plan to travel into the Bolivian Amazon later, you will absolutely need one.

Crossing the Border from Peru to Bolivia Overland

The most reliable way to cross is by taking a tourist bus from Puno, Peru, to Copacabana, Bolivia, via the Kasani border crossing. You must complete exit stamps in Peru, walk across the border, and complete entry stamps in Bolivia, keeping all paperwork secure for the duration of your stay.

Book a 'Direct' Tourist Bus. Purchase a ticket from Puno to Copacabana. Companies like Transzela or Titicaca Peru are common. 'Direct' means the bus takes you through the immigration process, but be prepared for a 30-minute stop at the border.
Clear Peruvian Immigration. When the bus stops at the border (Kasani), take all your luggage off. Go to the Peruvian migración office to get your exit stamp. Do not lose your PDI (Andean Migration Card) given to you when you first entered Peru.
Walk the Border. Walk the 100 meters across the border line into Bolivia. You will see a small building for Bolivian immigration.
Process Bolivian Entry. Present your passport. If you are a U.S. citizen, have your visa fee (usually $160 USD in crisp, clean bills) and printed documents ready. Most other nationalities get a stamp for free. Check that the entry stamp date is correct before leaving the booth.
Re-board the Bus. Your bus will be waiting on the Bolivian side. Board the bus and continue the 15-minute drive into Copacabana town.

Can I pay my Bolivian visa fee in credit card?: No. Bring the exact amount in clean, crisp US dollars. They will reject bills with even minor rips or ink marks.
Do I need a yellow fever certificate?: Not for entering Copacabana from Peru, but if you plan to travel into the Bolivian Amazon later, you will absolutely need one.