Which statement best defines the Tukey-Kramer test?

Why is it important to reject the omnibus ANOVA null hypothesis before performing Tukey-Kramer tests?

A researcher conducts an ANOVA to compare the mean systolic blood pressure among four different diet groups. The SPSS output gives a $p$-value of $0.012$. Using a significance level of $0.05$, what should the researcher conclude? Does the ANOVA test specify which diet groups differ in their means?

Given ANOVA output: Sum of squares (Error) = 134.4, df(Error) = 28, MS(Error) = 4.8. There are 4 groups with sizes 8, 9, 7, and 7 (N = 31). For the Tukey-Kramer procedure which MSE and error degrees of freedom will you use, and why?

A study with k = 4 groups and error df = 20 uses alpha = 0.05. You have computed q statistics: 3.10, 2.85, 4.20, 1.75, 3.95, 2.10 (six pairwise comparisons). If q_critical from the q table is 3.77 for these parameters, which statements are correct about significance and how many pairwise nulls are rejected?