Alternate approach for 1
SELECT employeeid,employeename,salary,hiredate
(
SELECT DENSE_RANK() OVER (ORDER BY Salary DESC) AS Rnk,*
FROM table
)t
WHERE Rnk=2


modified solution for 2 to take care of cases where there are ties ie multiple years with same maximum employee count

SELECT TOP 1  WITH TIES datepart(yy, hire_date) Year, count(employee_id) cnt
FROM YourTable
GROUP BY datepart(yy, hire_date) 
ORDER BY cnt DESC