Q factor in inductors
The graph shows the nominal or typical Q value that you can expect for a certain inductor at a certain frequency. Unfortunately not all these inductors will be identical, due to small variations in the materials and inaccuracies the Q will vary. Sometimes Q will be higher, sometimes it will be lower.

The table shows the minimum value of Q meaning that the manufacturer guarantees that the value of Q should never be lower than stated value (48 at 7.9 MHz).

Indeed for an inductor working at 300 MHz you will need a different type. No, the Q factor will not "recover" for higher frequencies. If there is a graph of the inductor's impedance over frequency you will see that the impedance will decrease over frequency at frequencies above the "peak Q" frequency so the inductor will behave like a capacitor !
That means that actually it does not matter what the Q is for higher frequencies as the Q is only relevant when the inductor behaves as an inductor.