Oh boy....
I think the Musée des Beaux Arts in Bordeaux (where I am at present) is one of the feeblest I've seen anywhere in France - tiny, dark, full of foreboding religious art - the best thing about it is the benches in the garden. The Musée d'Aquitaine and the Musée de Bordeaux and the Musée de l' Ethnographie are far more compelling.
There are several trams, and none of them starts at the train station, though two of them stop there. Neither of the C-line trams that go through the train station stops at Victoire, which is where the University of Bordeaux is located.
Brantôme is nowhere near Lascaux/Montignac. It's not even in the Périgord Noir. It's a nice enough town, but a terrible choice for accommodations if Lascaux and prehistory are your goals.
Taking the train from Paris to Angoulème defies all reason. Take the TGV from Paris to Bordeaux, then the train to Périgueux and pick up your car there. You'll be 40 minutes from Sarlat at that point.
Ribérac is a homely town bursting its seams with British expats. I would stay away from it. There are FAR better markets all over the Périgord Noir, namely: St-Cyprien on Sundays, Le Bugue on Tuesdays (big market) and Saturdays (small market), Lalinde (Thursdays), Montignac (Fridays), Le Buisson (Fridays), Rouffignac (Sundays), and of course Sarlat, Saturdays (big market) and Wednesdays (small market).
There is no place named Abyerre-sur-Drone. If capttimo meant Aubeterre-sur-Drone, it's in the Charente, an entirely different département from the Dordogne and nowhere near where you're headed.
Honestly................pffff! I fail to understand why people bother to offer information when they don't know what they're talking about.
I have visited Lascaux II many times and Lascaux IV twice. There is nothing the slightest bit sad about either of them. They are magnificent reproductions of the real caves, which of course one can't visit because visitors destroy them. The staff at both sites are incredibly informative, and the sites are very evocative. The fact remains that you simply cannot visit original caves in the Périgord except by permission (well, you can get into Font-de-Gaume with some serious planning, maybe for the next year or two), so why not go see what you CAN see - it's all wondrous.
As noted, Sarlat is only a 30-minute drive from Lascaux IV and Montignac. You could certainly stay in Montignac - it's a lovely town - but there's no reason to stay away from Sarlat. There are plenty of other places you could stay as well, along the route to Montignac: St-Léon-sur-Vézère and Plazac being two good choices. You could also stay in Les Eyzies and enjoy the Pôle and the Musée Nationale de la Préhistoire. If you decide to stay in Montignac, I can recommend a lovely B&B that is just minutes from Lascaux up in the hills.