Partial Answer

###Puzzle 3

The meaning of rebus:

CAKE - C (100 in roman numeral) + L (50 in roman numeral) = LAKE
KEY + N(3) + A(5) -> Insert N as 3rd letter and A as 5th letter = KENYA

LAKE IN KENYA

With addition, maybe the missing reindeer is:

Rudolph, the Red-Nosed Reindeer

Because:

One lake in Kenya is named Lake Rudolf (now it is Lake Turkana) in honour of Crown Prince Rudolf of Austria by dicoverer.

Partial Answer

Puzzle 3

The meaning of rebus:

CAKE - C (100 in roman numeral) + L (50 in roman numeral) = LAKE
KEY + N(3) + A(5) -> Insert N as 3rd letter and A as 5th letter = KENYA

LAKE IN KENYA

With addition, maybe the missing reindeer is:

Rudolph, the Red-Nosed Reindeer

Because:

One lake in Kenya is named Lake Rudolf (now it is Lake Turkana) in honour of Crown Prince Rudolf of Austria by dicoverer.

Partial Answer

###Puzzle 3

The meaning of rebus:

CAKE - C (100 in roman numeral) + L (50 in roman numeral) = LAKE
KEY + N(3) + A(5) -> Insert N as 3rd letter and A as 5th letter = KENYA

LAKE IN KENYA

With addition, it maybe means:

MAN-made lake in Kenya, which is Nakuru.
I still don't know which reindeer is missing.

Partial Answer

###Puzzle 3

The meaning of rebus:

CAKE - C (100 in roman numeral) + L (50 in roman numeral) = LAKE
KEY + N(3) + A(5) -> Insert N as 3rd letter and A as 5th letter = KENYA

LAKE IN KENYA

With addition, maybe the missing reindeer is:

Rudolph, the Red-Nosed Reindeer

Because:

One lake in Kenya is named Lake Rudolf (now it is Lake Turkana) in honour of Crown Prince Rudolf of Austria by dicoverer.