Hey @Jupyter123
For the Hint Text, it will have the same font size as of the normal text you want to enter in it. And the color cannot be changed.
For the two if statements, you just write && between them, if your require both of them to be true otherwise you can write || if you want it to be visible if one is true.
Something like below:

So, in your case it can be like:
OR Case:
If(
varCount < 3 ||
!IsBlank(TextInput1.Text)
,
DisplayMode.Edit,
DisplayMode.Disabled
)
And Case:
If(
varCount < 3 &&
!IsBlank(TextInput1.Text)
,
DisplayMode.Edit,
DisplayMode.Disabled
)