Questions for SSM2211

Dear Sir/Madam,

We have a question fo your SSM2211 audio amp.

We will use your SSM2211 as RF amplifier for more power output instead of current AD8018.

1)
As for Page-12 Figure-35
Thick Line=PHASE SHIFT
Thin Line=GAIN
Correct?

2)
As for same fig-35,
Does "GAIN" means currnet GAIN or voltage GAIN?

3)
Can I use this AD8018 as buffer AMP(Gain=1,voltage follower)?

4)
We need the big current drive amplifier more than 400mA except for AD8018.
We picked up SSM2211 due to have big output current and drive single ended +5V power supply.
If our this choice have a problem you think, so please advice it to us what is the problem?

Our rough signal chain;
3MHz FSK modulated signal -> DAC AD9762 -> this AMP -> Active LPF -> tranformer -> Antenna

Thanks Kaos