First time in Africa

Hi folks, hoping someone here can advise me...

I'm planning a trip to Africa starting in Tanzania, ending in South
Africa. I intend to transit Zambia, Zimbabwe and Botswana overland.

I need visas for Zimbabwe, Zambia and Tanzania, are these difficult to
get? They want a travel itinerary. I'll just have one that says I'm
flying into Dar es Salem, flying out of Cape Town.

Some more questions...

Is it still possible to travel overland from Dar Es Salem to Lusaka on
the train? My country's travel report says a particular crossing
between Zambia and Tanzania is closed, but I'm not sure if they meant
to put that it's not possible to pass this way.

I'm going first class on any train ride I take, my travelling
companion and I will book all four bunks if that's the best we can get
(for our own safety). What can I expect overall?

I love Ethiopian food (with the bread they serve it with), is that
what I can expect to eat (stuff like that without utensils) when I
head south?

How difficult is it to change money when entering a new country? I do
believe I cannot buy some currencies before I leave here. Where is it
prohibited to have any currencies when leaving? Does that include
pocket change?

Is there anything in particular I should bring with me (that we take
for granted at home), like toilet paper?

Should I be planning a specific itinerary and pre-booking hotels? Or
can I find accomodations when I get some place? (Major cities and the
like). Since we are travelling by train, and it's so unreliable, I'm
not sure if we can stick to a plan.

Is a month long enough to do this trip?

Thanks in advance,
S.