Other than prime numbers are all numbers multiple of 2,3,5 and 7 (Other Prime numbers as well). Suppose like if we need 8 it's the combination of 2.2.2, and 15 as 5.3 etc.
No: $$11\cdot 13 = 143$$
$$13 \cdot 17 = 221$$
The most we can say is what the Fundamental Theorem of Arithmetic tells us: Every integer greater than $1$ is a prime number or a product of prime numbers.
Edit: (Revised question) Yes, except $1$ is neither prime nor is it a product of prime numbers.
No, $1763 = 41 \times 43$. For example, if you multiply any two primes other than $2,3,5$ and $7$ (note there are infinitely many primes), you get a number that is "not a combination of" $2,3,5$ or $7$.
No . Fundamental theorem of arithmetic states that every integer greater than 1 is either prime itself or is the product of prime numbers
$22 = 11 \cdot 2$
$1200 = 2^4 \cdot 3 \cdot 5^2 $
It's not like that.
Every positive integer(non-prime) is always a multiple of other primes smaller than that.
But it doesn't mean that those will surely have 2,3,5,&7.
for example you can take: