First part
Let us assume we are working with two set $A$ and $B$ and we shall work gradually on all possible sizes of set $A$. We work the cases by finding for a given cardinality of $A$, the possible sets $B$ such that
$|A\oplus B| = 2$, where $\oplus$ is the symmetric difference operator. In other words we need to have $|A\cup B|=|A\cap B| +2 \tag 1$
CASE 1: When $|A|=0$ i.e $A=\phi$
then, $|A\cap B|=0$ and we need to choose two elements from $n$ elements to form set $B$, such that $(1)$ is satisfied. [vertex corresponding to set is $A$ is adjacent to all vertices which corresponds to sets of size $2$]
So number possible $B$’s = $^n C_2 = \frac{n.(n-1)}{2}$
CASE 2: When $|A|=1$ ; $A=\{ a\}$ $(say)$
(a) when $A\cap B=\phi$ then we should have only $1$ element in $B$ other than what is in $A$ and this can be done in $n-1$ ways. [vertex corresponding to set is $A$ is adjacent to all vertices which correspond to all other sets of size $1$]
(b) when $A \cap B=A$ then we should have in $B$ elements in $A$ and apart from that $2$ other elements than those in $A$. So the no. of possible $B$’s are $^{n-1}C_2=\frac{(n-1)(n-2)}{2}$ [vertex corresponding to set is $A$ is adjacent to all vertices which corresponds to sets containing $a$ of size $3$]
So total number of possible $B$'s $= (n-1)+\frac{(n-1)(n-2)}{2} = \frac{n(n-1)}{2}$
CASE 3: When $|A|=2$, $A=\{a,b\}$ $(say)$
(a) when $A\cap B=\phi$ this as per the question would mean that $B=\phi$ and there is only $1$ possible choice. [vertex corresponding to set is $A$ is adjacent to vertices which correspond to the null set].
(b) when $|A\cap B|=1$, then we can choose in $^2C_1$ the element of $A$ to be present in $A\cap B$ and the remaining $1$ element of $B$ should be chosen as $^{(n-2)}C_1$. So the number of possible $B$’s = $^2C_1 . ^{(n-2)}C_1 = 2.(n-2)$ [vertex corresponding to set is $A$ is adjacent to all vertices which corresponds to sets of size $2$ containing either $a$ or $b$ but not both].
(c) when $|A\cap B|=2$ then we can choose in $^2C_2$ the element of $A$ to be present in $A\cap B$ and the remaining $2$ element of $B$ should be chosen as $^{(n-2)}C_2$. So the number of possible $B$’s = $^2C_2 . ^{(n-2)}C_2 = \frac{(n-2)(n-3)}{2}$. [vertex corresponding to set is $A$ is adjacent to all vertices which corresponds to sets of size $4$ containing both $a$ and $b$].
So total number of possible $B$'s = $1+2.(n-2)+ \frac{(n-2)(n-3)}{2}=\frac{n(n-1)}{2}$
CASE 4: When $|A|=x$, where $x\geq 3$
(a) when $|A\cap B|=x-2$ then we can choose in $^xC_{x-2}$ ways the element of $A$ to be present in $A\cap B$ and the remaining $0$ elements of $B$ should be chosen as $^{(n-x)}C_0$. So the number of possible $B$’s = $^xC_{x-2} . ^{(n-x)}C_0 = \frac{x.(x-1)}{2}$ [vertex corresponding to set is $A$ is adjacent to all vertices which corresponds to sets of size $x-2$ containing any $x-2$ elements of $A$]
(b) when $|A\cap B|=x-1$ then we can choose in $^xC_{x-1}$ ways the element of $A$ to be present in $A\cap B$ and the remaining $1$ element of $B$ should be chosen as $^{(n-x)}C_1$. So the number of possible $B$’s = $^xC_{x-1} . ^{(n-x)}C_1 = x.(n-x)$. [vertex corresponding to set is $A$ is adjacent to all vertices which corresponds to sets of size $x$ containing any $x-1$ elements of $A$].
(c)when $|A\cap B|=x$ then we can choose in $^xC_{x}$ ways the element of $A$ to be present in $A\cap B$ and the remaining $2$ elements of $B$ should be chosen as $^{(n-x)}C_2$. So the number of possible $B$’s = $^xC_{x} . ^{(n-x)}C_2 = \frac{(n-x).(n-x-1)}{2}$. [ [vertex corresponding to set is $A$ is adjacent to all vertices which corresponds to sets of size $x+2$ containing the $x$ elements of $A$].
So total number of possible $B$'s = $ \frac{x.(x-1)}{2}+ x.(n-x)+\frac{(n-x).(n-x-1)}{2}=\frac{n(n-1)}{2}$
So degree of each vertex is $\frac{n(n-1)}{2}$.
Second Part
From the discussion above, we can see that all the sets of even cardinality are in a component and all the sets of odd cardinality is in another component. So there are just $2$ components in the graph.